* Remove extra AddField overload in EmbedBuilder

* Remove AddInlineField()

* Add GetReactionUsersAsync(IEmote) overload

Resolves #730

* Remove obsolete GetReactionUsersAsync(string) overload

* Changed Guild#DefaultChannel to resolve the first accessible channel

Resolves #776

This change is inline with hammerandchisel/discord-api-docs#329

RestGuild#DefaultChannelId is now obsolete and will throw a
NotSupportedException.

* RestGuild#DefaultChannelId will fall back to the guild ID

Adding an exception here would be a breaking change, so this was agreed
to fall back to the previous behavior, which would just return the guild
ID.

IChannel.IsNsfw will now return false when being used on any channel
that is not an ITextChannel. When being used on an ITextChannel, this
will now account for the API flag, and fall back to the channel name.

(this is gross design, thanks discord)

* Update RestRole.cs

Fix everyone mention.

* Update SocketRole.cs

Fix everyone mention.

* I'm good at this, I swear.

Seeing as D.NET will warn you about an impending BadRequest if you try and send an empty field, why not make it warn about the impending BadRequest if you try and send a whitespace field?

Fixed RestGuildUser not updating inherited RestUser properties

* Fix potential nullref in embedBuilder value setter

* Null check on footer iconUrl

* Adding checks for the other URL properties

* Adding IsNullOrUri extension

* Setting StringExtensions as internal

* Add embed builder extensions

People in #dotnet_discord-net suggested that this should be part of
the lib after I demonstrated it

* Move some extensions into EmbedBuilder [2]

Apparently git didn't like that previous commit

* Fix error with EmbedBuilderExtensions

A summary of issues which happened:
- Git decided to add an amend commit (I told it to quit?)
- VS Code thinks everything is an error so it wasn't helpful
- dotnet decided to think there was no error until I deleted all
  build outputs and rebuild

Sometimes I question my ability to use version control properly.

* Add support for audit log reasons

* Made changes per discussion

* Add various property validation in EmbedBuilder

* Embed URI changes

Changes property types for any URLs in Embeds to System.URI.
Adding field name/value null/empty checks.

* including property names in argumentexceptions

* Adds overall embed length check

Remove IUser.CreateDMChannelAsync / Fix SocketGlobalUser.DMChannel

* remove tip in docs about SocketEntity.Discord

* Expose the 'Fields' collection on EmbedBuilder

After some discussion I decided that there was really no reason to keep this private, and it didn't really go along with the rest of the design of the EmbedBuilder.

This is NOT a breaking change.

Exposing this property should not have any negative effects.

* Don't allow EmbedBuilder's Fields to be set to null

* Add IChannel.Nsfw, RequireNsfw precondition

* Refactored IChannel.Nsfw to IsNsfw, removed NsfwUtils

Per pull-request feedback

* proper nsfw channel check

* Update ChannelHelper.cs

* typo

* Removed GuildUserExtensions and moved the methods to IGuildUser and implementations

* Made changes per fox's suggestion: Change->Modify. New Modify overload.

* Oops

* Per Volt: reimplemented new endpoints

* Fixing broken docstrings

* I forgot that docstrings are XML

* Implemented atomic add/remove role endpoints

* Removed  so people aren't irked

* Added single-item role add/remove methods

Added support for reaction 'me' field

Automatic animated avatar detection

Fixed GetReactionsUsersAsync returning an empty enumerable