Changed error(...) to a weak function

Made error(...) a weak function so that it can be overridden in
production projects. Also fixed several serial_api.c files that required
stdlib.h, but were getting it from error.h.
Added AnalogOut for STM32F407 Discovery
Merge pull request #239 from neilt6/master

Changed error(...) to a weak function
Fixed location of BLE_API
Rename Code Red -> LPCXpresso
Merge pull request #240 from va7deo/DISCO_F407VG/AudioOut

Added AnalogOut for STM32F407 Discovery