Fix origin transform in DrawInternal with src rect

This change fixes a transform applied on the origin parameter
passed to DrawInternal, based on the ratio between the destination
rectangle and the texture width / height.

When a source rectangle has been specified, its size should be used
instead.
Fix edge-case when source rect has 0 width/height

Nothing would get rendered when the source rectangle had a width or
height of zero, whereas XNA does render something.
Added comments to Color
Color fix
Color comment fixes
#1244 Transparent versions of the logo graphics and icons.
#1245 Icons and graphics for use on a dark background.
updated comment regarding the missing 32x32 and 48x48 sizes for the dark background graphics.
TitleContainer.OpenStream() no longer accepts absolute paths.
ContentManager no longer passes absolute paths to TitleContainer.OpenStream().
Unified TitleContainer into a single implementation.
Unified TitleContainer into a single implementation.
Merge branch 'TitleContainer' of github.com:SickheadGames/MonoGame into TitleContainer
Merge pull request #1174 from elisee/fix_spritebatch_draw_origin

Fix origin transform in DrawInternal with src rect
Merge pull request #1302 from Shqrdx/test

Added comments to Color
Updated Readme.MD as requested in #1143.
Added jenkins build status image to header.
Tiny update.
Tiny typo fix.
Updated headings capital casing so they are consistent.
Merge pull request #1312 from raistlinthewiz/readme-md-update

Updated Readme.MD as requested in #1143.