Lowered image comparision tolerance slightly.
Using new technique for comparing frames which gives us much better matches.
Merge pull request #2875 from SickheadGames/testfix

Unit Test Image Comparision Improvements
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
Document Rectangle's public properties and fields, and remove some whitespace for consistency.
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