Merge branch 'release/v2_3_0' into dev
Fixed ptex cache resource release sequence.
Adjusted include order for clKernelBundle.cpp

Avoids GL declaration conflicts w/ OpenCL on OS X
Amend language of attribution file 'NOTICE.txt'
Fix build symbol conflict in Far

Override the destructors of the Hbr rotation operators to force the compiler to
inline them (they are no-op's)

fixes #229
Optimize a bit of ptex mipmap lookup.
Fix patch parambuffer generation in OsdD3D11DrawContext. Also fixes hlsl shader bug.
Add a DX11 version of ptex mipmap loader
Add DX11 ptex viewer (unfinished)
Fix a minor osdutil build warning (seen with gcc 4.8.1)
Add fractional partitioning, normal derivatives computation into hlsl shaders.
Ptex loader : Add memory usage limiting. Clean code styles.
ptexViewer : show ptex memory usage
dxPtexViwer : more parity to ptexViewer
Add face-varying boundary interpolation parsing to shape_utils

Also change face-varying data declarations: 2 channels of 1 float instead of 1 channel of 2 floats for uv's
improve ptex guttering.
Fix edge-only face-varying interpolation.

For face-varying interpolation, sharpness should be interpreted as an
infintely sharp boundary. Hbr implements this correctly for vertex
sharpness, but inconsistently for edge sharpness: both the fvarbits
cache and methods that gather face-varying sharpness need to be corrected.

fixes #231
This change adds simple HbrMesh and FarMesh wrapper classes to osdutil
and a projectTest example binary to test.  Currently projectTest crashes,
Manuel has been looking into the crash- thanks!
Added license headers.
Addding some video links to our collection of external resources.