Removed surface member and changed transform to defaulted parameter
Added new GpuContextManager class
Added new functions to GpuContext
Removed empty space
Added GpuSurfaceBin class
Added functions to GpuSurface
Adapted to changes in GpuContext and implemented resizeTo function
Now using temporary GpuSurfaces when drawing
Changed name of functions
Implemented recycle, dispose and now setting correct viewport when drawing
Adapted to change in GpuSurface.draw parameters and changed name of context variable
Simplified code
Merge pull request #6 from EmilWestergren/master

Added code for reusing OpenGL resources, handling multiple contexts and implemented resizeTo for GpuImages a