added assimp submodule.
Changed enet to come in as a submodule.
Uniforms in shaders follow C++ naming convention. Creation of uniform buffers requires passing a reflected type (to allow us later to use reflection to update uniforms that don't support blocks), small bug fix in program where we were returning sampler handle not index.
minor fixes to uninitialsed mem, and some fields now set as transient.
Improved SeJsonWriter to not write out double, and handle transient fields.