* Add simple ADC driver, with support for ADC1 and all channels.
* Export MicroPython ADC object with read_channel function.
* Add stm32f4xx_adc.c and adc.c to Makefile.
vstr is initially intended to deal with arbitrary-length strings. By
providing a bit lower-level API calls, it will be also useful to deal
with arbitrary-length I/O buffers (the difference from strings is that
buffers are filled from "outside", via I/O).
Another issue, especially aggravated by I/O buffer use, is alloc size
vs actual size length. If allocated 1Mb for buffer, but actually
read 1 byte, we don't want to keep rest of 1Mb be locked by this I/O
result, but rather return it to heap ASAP ("shrink" buffer before passing
it to qstr_from_str_take()).
You can now append a zipfile (containining uncomressed python sources)
to the micropython.hex file.
Use MEMZIP_DIR=directory when you call make, or set that in your
environment to include a different tree of source files.
Added sample /boot.py, /src/main.py, /test.py and /src/test.py files.
Added run command so that you can execute scripts from REPL (until import is implemented).
Added build directory to .gitignore
While updating the teensy Makfile, I noticed that the stm Makefile
was using calling arm-none-eabi-objcopy and size rather than
$(OBJCOPY) and $(SIZE), so I added these 2 for consistency.
* Add a TARGET definition to Makefile (default PYBOARD).
* Add support for discovery LEDs in led module.
* Add support for discovery user switch in usersw
* Add EXTI interrupt handler for discovery user switch on (PA0).
* Parameterize led and usrsw modules pins and port.
* Issue #83
Qstr's are now split into a linked-list of qstr pools. This has 2
benefits: the first pool can be in ROM (huge benefit, since we no longer
use RAM for the core qstrs), and subsequent pools use m_new for the next
pool instead of m_renew (thus avoiding a huge single table for all the
qstrs).
Still would be better to use a hash table, but this scheme takes us part
of the way (eventually convert the pools to hash tables).
Also fixed bug with import.
Also improved the way the module code is referenced (not magic number 1
anymore).
