Mostly cleanup of unused code.
Fixed linespacing to use the font metrics.
Removed unused usings.
Simpler conversion to alpha premultiplied greyscale.
Disabled border padding which is causign artifacts.
Use the font height for unrendered characters.
Document Point.Zero property.
Document Point.ToString() method
Document Point() constructor.
Fix typo in previous commit.
Merge pull request #2878 from dneelyep/develop

Add XML docs for a few items in MonoGame.Framework.Point.cs
Remove some #ifs
Removed SpriteFontDescription.CharacterRegions ( did not exist in xna ).
Added SpriteFontDescription.Characters
Removed SpriteFontDescription constructor taking a region list  ( did not exist in xna ).
Document Rectangle's public properties and fields, and remove some whitespace for consistency.
EffectParameter now shows its current value in the watch window.
Replacing string.Format calls with string.Concat
Merge pull request #2882 from dneelyep/patch-3

Document Rectangle's public properties and fields, and remove some white...
Merge pull request #2879 from danzel/patch-1

Remove some #ifs
Some GraphicsAdapter cleanup.
Cleanup and documentation pass.