Increase number of bytes per program packet in bootloader for increased speed.
Change bootloader linker script to give the bootloader its own settings area.

This is a bodge to fix an error when the settings area gets erased. It shouldn't be being accessed by the bootloader but its still causing debug messages to get dropped. When the proper flash filesystem storage mechanism is implemented we will have to fix this properly.
Change LED flashing pattern to make bootloader mode more obvious.