Moved pack shaders to general OpenGLES3Context class
Removed public functions for searching bins and getting specific shaders. Implemented general getMap function to get shaders from the context.
Added GpuMapType enum
Added upload function
Implemented upload function and moved searching image bins for recycling images from the image classes to the context
Adapted to change in context
Moved search in surface bin from Surface class to context class
Removed unnecessary getSurface function
Merge branch 'master' of https://github.com/cogneco/ooc-kean
Merge pull request #27 from EmilWestergren/master

Restructured some code