More /o adding for ExtUtils::Typemaps (dup'd code)
Drop duplicated code: make_targetable moves to EU::Typemaps

The make_targetable function in ExtUtils::ParseXS::Utilities now lives
in ExtUtils::Typemaps::OutputMap as method 'targetable'.
Fix targetable size detection; move tests

Also improves targetable tests by leaps and bounds.
Cosmetics: marginally more useful variable name
Improve ->targetable documentation
Simplify output typemap code generation (targetable)