stmhal - Add usart support
unix: Clean up includes.

Remove unnecessary includes. Add includes that improve portability.
py: Clean up includes.

Remove unnecessary includes. Add includes that improve portability.
objstr.c: Replace size_t with machine_uint_t.
Merge pull request #347 from dhylands/stmhal-usart

stmhal - Add usart support
stmhal: Remove unnecessary include.
Merge branch 'master' of github.com:xbe/micropython
stmhal: Add SD card support.

Just low-level read/write support.  No filesystem yet.
stmhal: Add autoflash script, to flash a DFU device automatically.
stmhal: Add flash write support and flash storage driver.
stmhal: Add fatfs support, working with flash and SD card.
stmhal: Add LCD driver.
stmhal: Add lcd.c to Makefile, and init LCD in main.
py: Fix bug in mpz int, where small int is on lhs, mpz on rhs.
py: Add comment about bugs in objint_longlong.c.
py: Add mpz modulo operation.
py: Add math.e constant.
py: Allow hashing of functions and tuples.
py: Fix int-longlong binary operations.
Added various simple functions to math module.