Function kernel_putchar changed: Tab '\t' supported; Function find_command and commandline_to_multistring changed; Add new command mem
TAB echo disabled in function kernel_getchar; Using VLA instead of kernel_alloc in function enter_shell, to workaround the BUG of function kernel_malloc (To Knob: Try to implement the 'Out of Memory' error and return NULL)
Kernel_alloc Bug Fixed
Merge branch 'master' of ssh://git.code.sf.net/p/kestrel-kernel/code

Conflicts:
	Saturn-V/S-II/memory.c