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>

I

The attr ranges could accept an interval of chars (according to ASCII). The attr ranges are mainly used by the plugins to define their attributes, e.g., see the attributes of this plugin.

The examples below could be

Is your feature request related to a problem? Please describe.
When using the built in agents, users cannot override the strategies.

Describe the solution you'd like
The constructors for the built in agents should take strategy as an optional argument that defaults to the parent's default strategy.