formatting and other cosmetics changes.
on Linux and OS X, disable console coloring if stderr is not bound to a terminal.
fixed formatting.
added parameters to texture store to enable tracking messages.

new parameters:

   texture_store.track_tile_loading  (boolean, default is false)
   texture_store.track_tile_unloading  (boolean, default is false)
   texture_store.track_tile_cache_size  (boolean, default is false)
renamed texture_store.track_tile_cache_size parameter to texture_store.track_store_size.
fixed Qt runtime warning.
improved log messages.
Fixed OSLBSDF cosine mult bugs.
Merge pull request #308 from est77/OSL_work

Fixed OSLBSDF cosine mult bugs.
added missing #include statements; a few formatting fixes.
Move CMake configuration file from "src" to top level directory
Made changes to child CMakeLists.txt to reference different location of top level CMake configuration file