Added dict.__new__ accepting list/dict + tests

Fix negative indexing issue.

Also fixed __getitem__.  Previously was using ->[key] which
would place a NULL value for the key if the key didn't exist.
Subsequent calls could segfault.

Conflicts:
	src/runtime/tuple.cpp
	test/tests/tuples.py

Some tweaks to better support C (as opposed to C++) compilation.
Can now compile extension modules using gcc, in addition to clang as before.

Merges PR #109

Support added to initialize a tuple using the tuple type class.  Allows
creation specifying positional or using the keyword argument 'sequence'.

Accepts iterables- tested with lists, tuples, sets, dicts and strings

Need to special-case some places in the keyword handling
since they previously assumed that they would first have
to check if the keyword name matched a positional argument,
before putting into the output **kw.

errnomodule.c is extremely simple and doesn't do anything complicated,
so this is more of a proof-of-concept for now.
The tricky stuff will most likely be around newly-defined types.

The previous code assumed that there was only one stack per
thread, which could be examined by looking at the current registers.
Generators complicate that, since we switch to a separate stack.
We still need to scan the original, main stack, which means that
we need to add some bookkeeping code that remembers what the main
stack was, even as we swap to and from generators.

Nothing major was wrong, but was trying to double-pass the
generator/closure arguments.

Previously the gc header had to be set and managed by the user of the GC,
which didn't make much sense.

Also took this opportunity to clean up a bunch of old cruft.

Also got rid of ObjectFlavors and AllocationKinds, in preference for
a GCKind which I think makes more sense.  Right now there are only three
different GCKinds, but I'm not sure if the previous AllocationKinds
should each get their own GCKind.

Conflicts:
	src/runtime/str.cpp
	test/tests/str_manipulation.py

Added capitalize and title functions for strings

Implement tuple.__add__, dict.__contains__ and builtin id() function

removed dict_contains.py
fixed merge miss in dict.cpp

The goal is to be able to use these as-is