Removed PRE_RECEIVE state

Mixed the PRE_RECEIVE state with IDLE. Both do the same thing, but
PRE_RECEIVE processed some of the received data (because the frame can
have variable size)
Serial error check and Plataform especific headers

- Added an check to RXERROR flag (if it is set, it will go to MB_START
reseting all the things)
- Added f28335 headers to Serial.c and Timer.c
- Removed DSP28x_Project.h from PlataformSettings includes. For
production projects, I suggest to remove DSP2833x_Examples.h and include
your own optimized file