This reuses as much str implementation as possible, from this we
can make them more separate as needed.

Also, readline uses system malloc, so for symmetry, use the same for
non-readline case.

Memory leaks in lexer/compiler

Move LED defs to mpconfigport.h

Conflicts:
	stm/main.c

* Fix PCGCCTL bug using address instead of value.
* Fix issue #211

* Move RTC code from main to a separate module.

* Add MICROPY_HW_HAS_LCD
* Add MICROPY_HW_HAS_WLAN
* Use feature test macros in main

Fixes segfault on callable("string").

Addresses Issue #207.

STM port crashes without this re-init.  There should not be any state in
the core py/ code that relies on pre-initialised data.

Implement octal and hex escapes in strings.

Add Generic Feature Macros to mpconfigport

* Add some generic feature macros to mpconfigport
* Move pin and port definitions from usrsw.c to mpconfigport

Conflicts:
	stm/main.c

Addresses Issue #199.

Also fixes a bug in the for-in-range optimiser.

I hope to remove break and continue byte codes in the future and just
use jump (if possible).