Perform all plane transforms through Matrix4 multiply to ensure correctness.
Only find the DirectX SDK when compiling with Visual Studio, as the headers are incompatible with MinGW. Fixed export statements for MinGW. Closes #142.
Rewrote viewport resolve / pingpong logic in View. Optimizes away unnecessary framebuffer copies and fixes #138.
Safety check to skip renderpath commands with no output names, could cause out-of-bounds indexing.
Set currentRenderTarget for safety in case the renderpath has no commands.
Fixed pass name in the sky plane technique.
Rename var name from <package>_INCLUDE_DIR to <package>_INCLUDE_DIRS.

See http://urho3d.prophpbb.com/topic9.html.