This saves a lot of RAM. Fixes#287.
Also fixed compilation of frozen_mpy.c to use supplied make rule rather than
builtin rule (supplied rule suppresses printing out the gcc command line).
Reworked frozen module support: clean up makefiles and handle multiple directories.
Modules to freeze are included as git submodules.
Add neopixel to circuitplayground express build.
Fixes#56
From https://github.com/pfalcon/berkeley-db-1.xx, which so far contains
pristine 1.85, but will get patches and compile warning fixes going
forward.
Berkeley DB 1.xx is BSD-licensed, and will form the basis of "btree"
simple database module.
This allows to build libffi from source together with micropython, and is
useful for cross-compilation. Support for this was already merged
previously, to use:
make libffi
make MICROPY_STANDALONE=1
(To both commands appropriate cross-compilition flags can be added).
