Merge branch 'kernel2' of https://git.uwaterloo.ca/b26feng/cs452Trainee into kernel2

include/buffer.h

include/error.h

include/hash-table.h

include/k2.h

include/timer.h

include/types.h

lib/Makefile

lib/buffer.c

lib/bwio.o

lib/bwio.s

lib/context-switch.o

lib/hash-table.c

lib/k1.o

lib/k1.s

lib/k2.c

lib/kernel.o

lib/kernel.s

lib/libbwio.a

lib/libbwio.q

lib/libcs.a