Addresses Issue #203.

mp_map_deinit() finalizes static map, mp_map_free() - dynamic.

Add basic implementation of bytes type, piggybacking on str.

Rework makefiles. Add proper dependency checking.

This reverts commit a215b09c.

Move file obj to separate module

There can be multiple emitters allocated during compile (eg byte code
and native).

Add support for freeing code emitter objects at the end of compilation.

Update conwaylife.py

Want common qstrs to be first in the list so they have the lowest ids,
so that in the byte code they take up the least room.

Allow qstr's with non-ident chars, construct good identifier for them.

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

* Move gc_collect from main to py/gc.c
* Define GC's memory boundaries in linker script
* Issue #220

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

Import statements have been moved to the top of the file.

Also, add qstr's for string appearing in unix REPL loop, gross effect
being less allocations for each command run.

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").