Converts generted pins to use qstrs instead of string pointers.
This patch also adds the following functions:
pyb.Pin.names()
pyb.Pin.af_list()
pyb.Pin.gpio()
dir(pyb.Pin.board) and dir(pyb.Pin.cpu) also produce useful results.
pyb.Pin now takes kw args.
pyb.Pin.__str__ now prints more useful information about the pin
configuration.
I found the following functions in my boot.py to be useful:
```python
def pins():
for pin_name in dir(pyb.Pin.board):
pin = pyb.Pin(pin_name)
print('{:10s} {:s}'.format(pin_name, str(pin)))
def af():
for pin_name in dir(pyb.Pin.board):
pin = pyb.Pin(pin_name)
print('{:10s} {:s}'.format(pin_name, str(pin.af_list())))
```
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
