+ Changes dark theme changes to a different css to respect future docfx.css changes
+ Merge featherlight plugin into the dark theme

* added UserDefaultAvatar to IUser

* pass ushort as discriminator

* removed unneeded ushort.parse

* Create new entities on each build call. Added Length property to EmbedBuilder.

* Resolve Length issues per #1012

+ Fix table color.
+ Change warning/tip/important tip color.
+ Change font to Titillium Web.
+ Other changes that's easier on eyes.

+	Starting from this commit, there will be overwrite files added to
	provide further details about certain APIs.

+ This commit also adds overwrites for CommandContexts; this allows for additional remarks for the class.

+ This gets rid of unnecessary compilation for the test project.

+ This change requires us to target the solution.
+ Due to docfx issues, we must specify a  upon metadata compilation.
    - Because of this, docfx may complain about missing targets.
    - If we don't target a specific TargetFramework, docfx will fail to recognize documents with multiple framework targets.
    - Further investigation may be required.

* Throw when attempting to modify a message not made by the current user

* Didn't realize the client is passed into the MessageHelper function

* Respond to feedback

* Update Users property for category channels

* Wrong property being used for Channels property

CategoryId is the category that "owns" this channel. That is actually impossible right now for category channels, so it returns null and get all channels wrongly.

* Resolve permissions for category

* Remove spaces

* Small fix for IChannel.GetUsersAsync

* Add guide for building the docs

* Add version to the footer of the docs

* fix links for readme

* change formatting of doc build readme

* proper capitalization of DocFX in readme

* Remove code tags around version