Make types uniform in the Python exposition

[Sceki]

Some problems/algorithms seem to have an inconsistent python exposition in terms of types.

For instance, in ../src/problems/dtlz.cpp we have:

dtlz::dtlz(unsigned prob_id, vector_double::size_type dim, vector_double::size_type fdim, unsigned alpha)

But in the ../pygmo/expose_problems_0.cpp it is exposed as:

dtlz_p.def(bp::init<unsigned, unsigned, unsigned, unsigned>

Instead of:

dtlz_p.def(bp::init<unsigned, vector_double::size_type, vector_double::size_type, unsigned> ...

A check for all these type consistencies seems thus necessary.