setup.py: close file handles after using them
Doctests: closer to working in Python 2 + 3 simultaneously
_PylibMC_IncrMulti: fix bad argument string

Previously, in 2.7: TypeError: argument 2 must be 1-item sequence, not str
set_behaviors C code: also accept longs and bools

This was failing in Python 2. While changing this, also return
the name of the type that was rejected.
pylibmc/__init__.py: fix doctests in Python 2 + 3

I really don't like this idiom of checking against known values
and making sure the result is True, but I don't see a better way
to handle the int/long distinction in Python 2.
Fix rest of doctests in Python 2 and 3

The doctest IGNORE_EXCEPTION_DETAIL directive is pretty much
required for this.