Add board support infrastructure for the pcDuino board.  There is not much there on the initial checkin

MTD NAND: Check if block number is out of ragne at top of loop, not bottom, to avoid some bogus transfers

LM: Don't initialize .data if running in SRAM.  Global missing intialize type.  SAMA5 NAND: Fix for read nand in smaller chunks

NXFFS: more NAND-Releated changes; don't fail if a block read fails.  That might just be a NAND uncorrectable bit error.  Make scanning of the device on startup optional.  This might have introduced some NXFFS issure -- To be determined