Implemented Texture3D class
Include Texture3D throughout shader.py, program.py and variable.py
Minor changes to textures.py
A bit of clean-up
Added testing for 3D textures
fixed Texture3D and added simple gradient example
Almar's fixes to Texture3D - glextTexImage3D and glextTexSubImage3D renamed glTexImage3D and glTexSubImage3D
Rebased off master
Cleaned up import
Defined GL_SAMPLER_3D in texture.py
Fixing whitespace
Fixed error in test from rebasing
Removed an erroneous import
Error in gloo/__init__.py
Added requires_pyopengl to Texture3D testing
Another attempt for requires_pyopengl
Attempt #3 for requires_pyopengl
Code formatting
More code formatting
A bit more code formatting