Extend normalize_tuple to visit dict comprehension
More string  conversion

* string -> char
* string -> double
Make std::tuple hashable

So that it can be used as a key for a dictionary.
Rework type inference combination

Relies on __combined rather than operator+. This is important to handle
tuples correctly, because

tuple<int,int> + tuple<int, int> == tuple<int,int, int, int>

while

__combined<tuple<int,int>, tuple<int, int>>::type == tuple<int, int>
Handle Y' rosetta code series

A very beautiful one, that once again raised a lot of errors...
Merge pull request #73 from franckCJ/master

My comments on the documentation
Auto conversion from tuple to list when possible

The basic idea is to *always* rely on core::make_tuple to create tuple
and on decltype(core::make_tuple(...)) to refer to the type of a tuple.

The one can overload core::make_tuple to return a ltuple instead of a
tuple when all parameters have the same type. A ltuple is just a list
with another type. So it is iterable etc and behaves fine with pythonic.
And the extra type information makes it possible to convert it to a
tuple when going back to the Python world .

This commit closes #70.
Merge branch 'master' of github.com:serge-sans-paille/pythran