Update .gitignore. Ignore *.swp and *~.
Implement malloc and free.
Implement sbrk.
Decrease heap size
Define SYSCALL_ROUTINE macro to deal with syscall routine.
Update .gitignore. Ignore *.swp & *~.
Merge branch 'malloc'
Merge branch 'syscall'

Conflicts:
	src/syscall.s
Fix: RAM overflow. Enlarge RAM size.
Now can declare more space for heaps.