include ExecutableCTarget in main __init__ and docs
Just a bit of cleanup here -- include the ExecutableCTarget in init.py such that it can be accessed via from loopy import ExecutableCTarget
, include it in the autoclass docs, and finally check for an executable target in the CompiledCKernel
(as the CKernelExecutor
is only instantiated from ExecutableCTarget
, although we could just eliminate this assert and assume it to be true).
This last one is more of a directional question -- do we want to make a physical distinction between executable targets and codegen targets? This is already the case for PyOpenCLTarget
and OpenCLTarget
(and now the base CTarget
\ ExecutableCTarget
) -- in the future I would extend this to, e.g., ISPC.