[Cython] Fused types syntax

[Robert Bradshaw]

In looking at merging fused types, it's time to nail down the syntax.
The current implementation is

    ctypedef cython.fused_type(list, dict, object) fused_t

This requires an addition to the grammer to allow the "call" syntax in
a type declaration, as well as special casing to make it allowed only
in a typedef. What about

    cython.fused_type[list, dict, object].

One advantage is that indexing is already valid in type declarations,
and its the typical syntax for parameterized types. Thoughts? Any
other ideas?

- Robert


P.S. Anyone remember buffers and C++ templated types are dissallowed
as typedefs?