foundation for complex numbers
made __module__ a member descriptor for functions
Rearrange the LICENSE's a little bit

Looks like we're going to be using much more CPython code than just
in lib_python, so call that out specifically in the main LICENSE file.
Implement execfile() (1-arg version)

Also required adding some string functions so that
we could use os.path.
Import math module
Some functions are currently just stubs and I had to disable a
test which checked for a math exception because our C-API does
not support exceptions yet.
This is also yet another performance regression,
because patchpoint does not yet work for the C-API.
Fix computeFixedPoint

Was not being careful about distinguishing starting states
vs ending states... I'm not sure why that worked at all.

Also include Marius's optimization from PR #137

This is currently only being used by the DefinednessAnalysis which
could probably have a much faster algorithm.
Add some top-down timing measurements to compilation

Somewhat confusing, since us_compiling_analysis_liveness is
also contained in us_compiling_irgen, and I'm not sure of a good
way to avoid that for now.

But anyway, for "import re", the breakdown is roughly:
- 215ms definedness analysis
- 50ms liveness analysis
- 80ms phi analysis
- 200ms type analysis
- 5ms irgen
- 25ms other compilation stuff
- 40ms non-compilation time
Basic metaclass support

We actually had most of the base support in place; this commit just adds
the ability to specify a metaclass other than type_cls, and the ability
to determine which metaclass to use when defining a new class.

But just like how we have the base functionality to inherit from all the
builtin types but haven't updated all the functions yet, I bet there
are more places that assume the type of a class is always type_cls.
Very basic old-style class support

The mechanics for creating one actually seem pretty simple:
you just pick a different metaclass (ClassType).

I think the old-style classes are working ok now, but the old-style
instances very much are not.
fixes from kmod's code review
real and imag member descriptors