interp: no more static _setup

This patch is intended to make the interpreter lifecycle more controllable
and several independent interpreter instances per process possible

the arrays in interp_arrays.cc may remain static since they are read-only
and hence shareable between interpreter instances
interp: adapt exposure of _setup members

This employs the sledgehammer method of Python exposure: given a
verbose enough wrapper, everything can be exposed. There are
certainly ways to do this more elegant.

_setup.remaps remains unexposed for now - pretty sure the
introspect runtes was the only using code for this member
tests/interp: adapt remap/introspect

self.remaps not exposed for the time being
interp/setup_struct: add ctor, dtor
interp/setup_struct: constructor definition
interp/Submakefile: add interp_setup.cc