Added doxygen comments to PolyUIScrollContainer.h
Added an index file to doxygen to interlink modules.
Updated core cmake files to not rebuild stuff that is up to date.

The method is a bit "messy"(generating an empty file to indicate the date at which the target has last been built), but it seems to work fine.

Main advantage is that you can now change .cpp files, and the lua bindings will not be regenerated because of it.
Removed Entity::qPitch/Yaw/Roll

These were protected, and grep revealed they were not used anywhere.
Converted Entity::tags to a pointer.

The idea is that most entities don't use tags, so wasting space on it when it's not needed isn't a good idea. tags is protected, so this does not affect the public API. All the functions that use tags were updated appropriately.
Merge pull request #265 from CIB/less-memory

Entity memory optimizations
Merge pull request #259 from CIB/cleanup

Type-safety helpers for ObjectEntry
Merge pull request #258 from CIB/documentation

Documentation stuff
Added a shader clearing call in ScreenMesh rendering, fixed zlib URL
Added an instance of the Logger to CoreServices and added a nonstatic log method called logBroadcast that dispatches a notify event from the Logger instance so that they can be printed to listening consoles. Made the GLSL module use the log broadcast for its error message. Made IDE console listen to Logger broadcasts.
Merge branch 'gui-editor' of github.com:CIB/Polycode into gui-editor
Updated linux makefile.