Compile error due to case sensitive on Linux

[KuribohG]

Thank you for this awesome project! I think this is a really good starting point to learn USD & Hydra. This project helped me so much!

There is a compile error on Linux. Since Linux has case sensitive file system, shadergen.* is not the same as ShaderGen.*. This caused CMake error and C++ compile error (because compiler cannot find shadergen.h header).

Here is my solution for this error:

• Rename shadergen.h and shadergen.cpp to ShaderGen.h and ShaderGen.cpp
• In gatling/src/gi/src/gi.cpp, modify the included file name

[pablode]

Hi - I'm glad this project helped you! Thanks for the report; I've fixed the issue like you suggested in commit 1f0b539.