[ gitignore ] *.native
[ cleanup ] Cleaner Signature for sparseVector

* We know define a module type `S` and populate it with the functor
  `Make` exposing some constraints.
[ feature ] Adding matrix multiplications

* We define an extended signature for Vectors built on top of a
  `Ring` rather than an  ̀AdditiveGroup`: one can sum the pointwise
  product of 2 vectors' elements

* This lets us define matrix multiplication quite smoothly.
  Untested though. The next goal is quite clearly to fix the test
  suite and hunt down eventual bugs.