- still problems compiling context switch assembly
- related to -mthumb flag
- not a stable commit
	modified:   ../../boards/beaglebone/Makefile.include
	modified:   ../../cpu/xam3359/Makefile.include
	new file:   ../../cpu/xam3359/context.S
	new file:   ../../cpu/xam3359/exceptions.S
	modified:   ../../cpu/xam3359/thread_arch.c