Modify malloc function. Now use alloca function to request space. But it is still not work properly
Implement sbrk() and allocate heap space.
fix pb init location.
Implement malloc and free.
Change sbrk prototype
Call sbrk in match type, and simplify code style. Change pb and heaps design.
Add <stdint.h> and now can declare the exact length of alignment base.
Ensure proper alignment base.
Add 'mmtest' command which used for test malloc.
Fix sbrk typo.
Merge remote-tracking branch 'origin/malloc'

Conflicts:
	src/kernel.c