Parameters functional

[FlorentinGuth]

List of changes:

• uses '.' instead of '/' as a name delimiter in the container tree (to mimic pytorch)
• tentative changes to rnn parameters names to resemble more pytorch's,
• Functional container designed for use in Sequential,
• ~clang-format~.

[goldsborough]

Note: in general you should avoid formatting codemods intermixed with functionality. I have no idea what to look at in the changed files and have to expend brain energy understanding whether you changed functionality, or just changed the formatting, for each line. Please revert the clang-format changes if possible.

[FlorentinGuth]

I've reverted the formatting changes, sorry about that! I think I should probably add a test to verify that param() is consistent with parameters()?