:core ResourceManager#get now uses ResourceHandle.

THe direction I'm wanting is where ResourceManager just abstracts the
leg work of house keeping resource handles, resource handles deal with
obtaining the type of resource, and resources can be 'delayed'. E.g.
making a OpenGL dependant stuff initialize on first use when it gets
rendered.
:core faulty ResourceManager#unload for testing.
:core convenience method for load+get on String.
:core rewrite shader/program code.

There's no more GlslProgram and GlslShader -- I've never really expected
this to use another graphics API, plus there's already the OpenGl
adapter to handle OpenGl access.

GpuProgram and Shader now are concrete classes rather than interfaces.

Most of what's in Mesh is commented out, it was only test-stuff anyhow.
Freshen tags file.
:core new ResourceManager#load() is no longer a dummy.
:core ResourceHandle asShader now works.
Add dummy Texture interface.
:core ResourceHandle#asShader now closes it's file handle.
:pc Fix stupid typos.
:core remove deprecated C class.
Drop depreciated ShaderFactory.