Add caustics, IBL, lots of stuff :)

common/GL_utilities.c

gen_sample_points.py

shaders/env.frag

shaders/fbo.vert

shaders/ground.frag

shaders/hdr.frag

shaders/ibl.frag

shaders/skybox.frag

shaders/surface.frag

src/HDRLoader.cpp

src/HDRLoader.h

src/hdr.cpp

src/hdr.h

src/main.cpp

src/surface.cpp

src/surface.h

textures/autumn_field_puresky_ibl.hdr

textures/autumn_field_puresky_ibl_spec.hdr