Add an error check on updating cuda buffer.
Add face varying macros for loop subdivision
New example : uvViewer, to see how face varying interpolation rule works
Fix face varying rendering on loop surface
fix msvc warnings
fix the file permission on osd/ptexMipmapTextureLoader.cpp
Fix a bug of bad fvar splicing for loop surface.
Fix ptexViewer build with GLFW 2.x
Adding license & attribution files, as per Apache license requirements.
ptexViewer : add surface normal mode, use ptex cache for faster mipmap generation
Amending Apache license language & file headers.

New text:

     Copyright 2013 Pixar

     Licensed under the Apache License, Version 2.0 (the "Apache License")
     with the following modification; you may not use this file except in
     compliance with the Apache License and the following modification to it:
     Section 6. Trademarks. is deleted and replaced with:

     6. Trademarks. This License does not grant permission to use the trade
        names, trademarks, service marks, or product names of the Licensor
        and its affiliates, except as required to comply with Section 4(c) of
        the License and to reproduce the content of the NOTICE file.

     You may obtain a copy of the Apache License at

         http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the Apache License with the above modification is
     distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     KIND, either express or implied. See the Apache License for the specific
     language governing permissions and limitations under the Apache License.
Adding documentation for the uvViewer example
Add a note in the documentation about disabling offsetof warning.

Because client code inlines Hbr, this warning is spurriously triggered by
several compilers and needs to be disabled within the client code build system.

fixes #227
Update release notes
Release 2.3.0
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