Added ability to embed images within generated object files / c source

You do this by not including an image in the argument list.

Also added statically/aot-compiled tests.

Also renamed a few things that were too overloaded:
  - CodeGen_GPU_Dev::compile meant something different to CodeGen::compile
  - CodeGen::buffer_t meant something different to buffer_t
Merge branch 'master' of github.com:halide/Halide

Conflicts:
	src/CodeGen_PTX_Dev.cpp
Typo fix.