fixed bug in find_compiler.cmake
and find_boost.cmake
Added Volume.h
Added VolumeLoader.h

Integrated laoding of Volumes
Integrated managing of VolumeNodes
Integraded compositing of Volumes in CompositePass.cpp
texture upload_to() change from protected to public
Cleanup Volume Rendering Code in compose.frag
Merge branch 'develop' of https://github.com/vrsys/guacamole into windows_port

Conflicts:
	cmake/modules/find_compiler.cmake
	src/gua/renderer/CompositePass.cpp
Merge branch 'develop' of https://github.com/vrsys/guacamole into windows_port
PostFXPass used only pipeline::shading gbuffers, change to pipeline::compositing,

TODO: Use pipeline::shading gbuffers only and read write in to this gbuffers using them in pipeline::compositing
Remove whitespaces.
Change to shading.