[Cython] __future__.division on constants and C integers

[Stefan Behnel]

Stefan Behnel wrote:
> in the current implementation, __future__.division only applies when
> dividing non-constant Python values
> [...]
> My opinion on this is: if you request true division semantics by importing
> __future__.division, you should get true division in all places where you
> use the "/" operator.

I committed the change in

http://hg.cython.org/cython-unstable/rev/a3ad25325fe4

I may be a little more complicated than necessary, but it works in all
cases I could come up with (see the end of the changeset for tests).

Stefan