Improve method lookup in mp_obj_class_lookup.

Now searches both locals_dict and methods.  Partly addresses Issue #145.
Merge branch 'master' of github.com:micropython/micropython
Add MP_OBJ_TYPE(o) accessor.

Should not be overused, but when needed, it's needed.
rt_is_true(): Start with testing for (expected) boolean values.
Add rt_resolve_method() which doesn't throw exception if method not found.

Unlike previosuly existing rt_load_method().
Add skeleton implementation of array.array and bytearray.

So far, only storage, initialization, repr() and buffer protocol is
implemented - alredy suitable for passing binary data around.