First draft support for C stubs generation using ctypes

Still not working, but the piece are almost all there.
[WIP] more work on the C stub generation

Not working yet (not even compiling)...
WIP
Use ocamldep to infer dependencies in a directory

Seems that the API is not easy enough to use, with few convenient functions and goodies to help the user:
- use ocamldep instead of specifying the dependencies manually
- The C stub generation is compiling (need to test it now)
- The test API is a bit more complete (can now run sequence of commands)

The library bootstraps again. Really need to test the C stubs generation and then cut a release.
Fix distclean
Test disclean as well
Search for all sub-modules recursively in OCaml.modules
Improve docs
Really fix the description of submodules in OCaml.modules
More progress to get the Ctype stubs working

Not yet there, but closer ...
Add some Ctype stubs generation examples
C stubs gen are closer to work

Need to correctly generate the dll files and that should be fine.
Compile the C files properly

Still need to tunnel that through the stubs dependencies.
Support C objects in a library
Fix opam file.