migrate enc module to stm32f4
enlarge buffer for CDC for stm32f4discovery to hopefully resolve xmodem issues
Copy explanatory comments to avr, at91 platform_generic
eLua - grammar fix comments
eLua - UART - add platform constants for mark and space parity
AVR32 - Remove useless compares (unsigned < 0), clarify comments
LM3 - Add PWM disable macros
eLua - Disambiguate duplicate serial.h
(renaming fixes name overlap with serial.h in SAM drivers)
eLua - Remove redundant includes
duplicate files included by platform.h/platform_conf.h
eLua - modules - remove redundant includes
eLua - fix warning about using signed character as argument to isdigit
eLua - modules - suppress warnings on arguments to isdigit, etc.
eLua - clarify function prototypes - list arguments as void
Lua, eLua - Add function prototypes, fix shellh_ask_yes_no prototype
eLua - fix wrong # arguments, add type casts, add const attribs
eLua - add attributes for printf checking
eLua - add autorun files for WOFS, SEMIFS
eLua - platform_conf.h - update many out of date references

The material that used to be in platform_conf.h has
been split to several files, including:
platform_ints.h, cpu_xxxx.h, and in the board.lua.

Still more fixes needed in documentation.
LM3s - Fix PWM disable macros, add SPI disable checks
build_data.lua - merge arch CortexM3 and CortexM4
The arch just refers to toolchain and endian.
Platform build files handle core differences (like M3 vs M4).