+ Starting from this commit, all return types for tasks will use style similar to most documentations featured on docs.microsoft.com

References:
https://docs.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.dbcontext.-ctor?view=efcore-2.1
https://docs.microsoft.com/en-us/dotnet/api/system.io.filestream.readasync?view=netcore-2.1
https://docs.microsoft.com/en-us/dotnet/api/system.io.textwriter.writelineasync?view=netcore-2.1#System_IO_TextWriter_WriteLineAsync_System_Char___
And many more other asynchronous method documentations featured in the latest BCL.

* Mark guild as optional for invite

* Mark partial InviteMetadata members as Optional<T>

* Some of them aren't sent when requesting through the general GET invite endpoint

* Remove GetInviteParams

* It was kinda stupid in the first place, might as well always get the count instead of having to ask the user whether they want the two fields filled or not.

* Add ChannelType property

* Add vanity invite support

* References
https://docs.microsoft.com/en-us/dotnet/api/system.argumentnullexception?view=netframework-4.7.2
https://docs.microsoft.com/en-us/dotnet/api/system.platformnotsupportedexception?view=netframework-4.7.2
https://docs.microsoft.com/en-us/dotnet/api/system.badimageformatexception?view=netframework-4.7.2

* Fix ' />' caused by Agent Smith oddities
* Fix styling to be more specific about the mention of IDs

* ConnectAsync(bool external) API implemented

This allows developers to handle the AudioClient externally (for example with Lavalink)

* Modify ConnectAsync API and add DisconnectAsync to IAudioChannel

* Update summary message on IAudioChannel.DisconnectAsync()

* Review changes:
- Fix `if (!external)` styling
- Remove unecessary ConnectAsync overload

* SocketVoiceChannel overload update

* Update IAudioChannel.ConnectAsync()
- Remove ConfigAction from parameters
- Add SelfDeafen/SelfMute to parameters

* Remove SocketVoiceChannel.ConnectAsync() default params (Inherit)

* fix channel permissions modify parameter to use nullable boolean, correct default value

* Add general tests for the ChannelPermissions.Modify method to test default values

* remove unused cast in tests

* add guildpermission modify no param tests

* Add no-param modify tests for OverwritePermissions

* fix inconsistent parameters in GuildPermissions cstr

* Adjust formatting of methods and cstrs with many parameters

* remove temp file that was included. no idea what that is

* Fix System dependency

I should really stop fixing merge conflicts in the github website.

* Fix #995 ICategoryChannel.CategoryID throws NotSupportedException

* Add tests

* change run mode of TestChannelCategories

* Add throw for GetCategoryAsync

* Add xml doc explaining why exception is thrown

* Add test coverage for text and voice channel categories

* initial implementation of INestedChannel

* more implementation of INestedChannel design

* Add case in RestChannel Create for Category type

* set the CategoryID for RestVoiceChannel

* rewrite channel category tests to work with existing pattern

* remove outdated todo

* Make IVoiceChannel implement INestedChannel

* remove redundant interface implementation

* Add c#7 feature from feedback

* Remove redundant GetCategoryAsync methods from socket entities

* Added configureawait to async methods

* change signature of interface GetCategoryAsync

* Add check for cachemode in rest channel GetCategory

* remove redundant IGuildChannel interface from ITextChannel and IVoiceChannel

- Replaces the usages of `ReadMessages` with `ViewChannel`
- Renames the read message parameters of `GuildPermissions#Modify` to be view channel as well

* Update deps, fix test warnings.

* Support ns2.0

* Fix typo

* Remove ns1.1 support

* Net.Http and Net.Websockets.Client are not needed in ns2.0

* Move to net46 per volt

* Remove ns1.3 constants

* Deprecates ReadMessages, introduces ViewChannel

* Adds period and comma somehow missed

* Implement DeleteMessageAsync

* Refer to MessageHelper instead of duplicating call

* Fix refactor error

commit fa33034267
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sun Apr 29 13:50:56 2018 +0900

    Use built-in symbol

    refs: https://github.com/RogueException/Discord.Net/pull/1043#issuecomment-385223999

commit 27ea826685
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sun Apr 29 11:29:31 2018 +0900

    Add support casting System.Drawing.Color to Discord.Color

commit 1ab9de2497
Merge: f5bb99c7 a4d1e2bc
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sun Apr 29 10:16:46 2018 +0900

    Merge remote-tracking branch 'upstream/dev' into dev

commit f5bb99c77d
Merge: 3be8e40d b8b59d97
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Tue Apr 10 11:07:36 2018 +0900

    Merge remote-tracking branch 'upstream/dev' into dev

commit 3be8e40d38
Merge: c692306f 9d77a3cd
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sun Jan 7 15:05:31 2018 +0900

    Merge remote-tracking branch 'upstream/dev' into dev

commit c692306fcc
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sat Nov 11 10:49:00 2017 +0900

    Add target of the internal fields

commit 2d08f9a655
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sat Nov 11 10:17:42 2017 +0900

    Add some more extension

commit 4f19b835ff
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sat Nov 11 01:19:11 2017 +0900

    Add naming rules

commit af756cd9fe
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Sat Nov 11 00:35:30 2017 +0900

    Add basic .NET style rules

commit 503ece558b
Author: Acid Chicken (硫酸鶏) <root@acid-chicken.com>
Date:   Fri Nov 10 22:36:52 2017 +0900

    Add EditorConfig

commit 07bca5b31a
Author: Joe4evr <jii.geugten@gmail.com>
Date:   Fri Apr 6 09:44:50 2018 +0200

    Add ability to specify parameters on channel creation

commit 114e5b431b
Author: HelpfulStranger999 <helpfulstranger999@gmail.com>
Date:   Sat Apr 28 19:08:35 2018 -0500

    Fixes lack of default value for tts

commit 1fd8c70c53
Author: HelpfulStranger999 <helpfulstranger999@gmail.com>
Date:   Sat Apr 28 15:21:11 2018 -0500

    Makes text parameter of sending messages optional

* Cleaned up and refactored slightly

* Resolves #971

* Adds support for default avatars and resolves #971

* Amendment

* Final amendment

* Paginating reactions

* Amendments based on feedback

* Further amendment based on review

* Final(?) amendment

* Removes default limit and after user id

* Removes fromUserId; cleans up model creation; replaces function with individual parameters

Previously, Voice channels did not have ViewChannel in their "all" permissions

* Copy audit logs impl from old branch and clean up

I suck at using git, so I'm gonna use brute force.

* Remove unnecessary TODOs

Category channels do not provide any new information, and the other
I forgot to remove beforehand

* Add invite update data, clean up after feedback

* Remove TODOs, add WebhookType enum for future use

WebhookType is a future-use type, as currently audit logs are the only
thing which may return it.