Arrex

- bug fixes in unsigned comparisons in some methods
- fixed missing cython file in the package, causing the compilation to fail if cython were present

This update brings many fixes:

- fixed memleak in item access (`typedlist.__getitem__`)
- fixed memleaks in `typedlist.index`, `typedlist.reverse`
- fixed concatenation with buffers with a size not multiple of `dtype.size` that could lead to ambiguous behaviors

This release is much more usable than the previous one. It brings the following:

- a complete rework of the concept of dtype
- a dtype system allowing pretty much anything to be a dtype, declared through a ddtype (see documentation coming)
- a native way to use python ints/floats in `typedlist`
- stronger tests
- few bug fixes

That first version provides an overview of the module functions:

**typedarray** a dynamically sized array
- ref-counted internal buffer
- flexible dtype, not known by advance
- copyless views and slices