+ Stylized option menu
+ The menu now defaults to whatever theme being the most preferred one

+ 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.