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.
Song.FilePath now an absolute path on desktop and Windows Store systems.
Song.Position and Song.FilePath are now internal as they are not part of XNA.
Added song support for Windows DX desktop builds.
Merge branch 'develop3d' into windesktop
This is a fix for #1280. Added lock around the access to the sound effect management lists. Also changed the use of HashSet in lieu of List.
Song.Duration property implementation

Reads the duration from xnb file while ContentManager is loading the
song
Merge pull request #1288 from aghajani/skywave

Song.Duration property implementation
Merge branch 'windesktop' of github.com:SickheadGames/MonoGame into windesktop
Merge pull request #1272 from SickheadGames/windesktop

Song Support for WinDX
Song.Duration property implementation fix

Android and Linux Song class implementation to support Duration (read
the duration from .xnb file while loading the song)
Merge pull request #1290 from aghajani/skywave_song_2

Song.Duration property implementation fix
Ouya: Correct Y direction of axis
Merge branch 'develop3d' of https://github.com/mono/MonoGame into pull1291
Resuming a paused sound was not working correctly
due to a guard in Play that prevented the same instance being played twice.
Now also protects against Resume and Pause being called many times.
Fixes issue #1263.
Merge pull request #1292 from slygamer/issue1263

Resuming a paused sound was not working correctly
Merge pull request #1282 from totallyeviljake/ISSUE_1280_R1

This is a fix for #1280. Added lock around access to management lists.
First run PVRTC Support for the pipeline.
Changed function name in PVRTexLibC. Added configuration for x64.
Added PVRTCBitmapContent.
Merge branch 'develop3d' into FontProcessor
PVRTCBitmapContent is no longer a public class.