This commit rewrites the remarks section of GetMessagesAsync, as well as adding examples to several methods.

+ Geez, I didn't know there were so many.

* Change all Select(... as ...) to OfType

* Add changes according to 194a8aa427

Nullable<T> is not valid for Attributes, this is my suggested fix.

* Don't attempt instantiation of an abstract module
* Attempt associating a TypeReader in case one is registered late (ie. OnModuleBuilding)

* Added GetJumpUrl() as an IMessage extension method

* Removed extra line for consistency

* Moved the namespace from Discord.Commands to Discord

* lint: remove eof newline

* lint: use TextChannel to get GuildID

* 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

* 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

* Add ability to support different types of quotation marks

* Added normal quotation mark to list of aliases, removed single quote mark

* clean up leftover changes from testing

* change quotation mark parsing to use a map of matching pairs

* remove commented out code

* Fix conventions of the command parser utility functions

* change storage type of alias dictionary to be IReadOnlyDictionary

* revert type of CommandServiceConfig QuotationMarkAliasMap to Dictionary

* minor formatting changes to CommandParser

* remove unnecessary whitespace

* Move aliases outside of CommandInfo class

* copy IReadOnlyDictionary to ImmutableDictionary

* minor syntax changes in CommandServiceConfig

* add newline before namespace for consistency

* newline formatting tweak

* simplification of GetMatch method for CommandParser

* add more quote unicode punctuation pairs

* add check for null value when building ImmutableDictionary

* Move default alias map into a separate source file

* Ensure that the collection passed into command service is not null

* Add a dedicated TimeSpan reader so it doesn't suck

* Pass input as lower case

* Expose the internal entity type readers

* Add BestMatch property to TypeReaderResult for easily accessing the parsed object

* Allow setting IgnoreExtraArgs on an individual basis

* Remove passing in the flag as a separate parameter

* VS plz

* Push the RunMode setting out to its own attribute, because fox wants consistency.

Bonus: Removes the need for that godawful 'RunMode.Default'.

* Revert previous commit

* Fox doesn't like module-wide switches 😒