stmhal: Working STM32F4DISC accelerometer, via Python script.

Thanks to David Siorpaes.
Merge branch 'master' of github.com:micropython/micropython
objstr: Make sure that bytes are indexed as bytes, not as unicode.

Fixes #795.
modzlibd: Decompress part of "zlib" module, based on miniz tinfl.c .
modzlib: Add tinfl.c from miniz SVN repo, r63.

The only change is line-ending convesion to LF.
tests: Add test for zlibd module.