Fixed issue #127
Fix a Color3.cs ToString formatting indexes.

Red was being excluded since the indexes start from 0, not 1.
[SharpDX] Reduced code duplication in string formatting for Color3 and extracted text to constant
[SharpDX.Tests] added unit test for MathUtil.Wrap methods
[SharpDX.Tests] fixed some test cases for MathUtilWrapTests
[SharpDX] Fix behavior of MathUtil.Wrap methods for int and floats
[SharpDX] Add properties for rectangle size and corner positions