Added buffer to the console

Added hotkeys to switch between console buffers and to return to the home one
Added clear screen command
Added debug text outputs to the hello command and when loading sh

usys.S

@@ -1,37 +0,0 @@
-# Generated by gensyscalls.pl.  Do not edit.
-# To change syscall numbers or add new syscalls, edit gensyscalls.pl
-
-#include "syscall.h"
-#include "traps.h"
-
-#define SYSCALL(name) \
-.globl name; \
-name: \
-	movl	$SYS_ ## name, %eax; \
-	int	$T_SYSCALL; \
-	ret
-
-SYSCALL(fork)
-SYSCALL(exit)
-SYSCALL(wait)
-SYSCALL(pipe)
-SYSCALL(read)
-SYSCALL(kill)
-SYSCALL(exec)
-SYSCALL(fstat)
-SYSCALL(chdir)
-SYSCALL(dup)
-SYSCALL(getpid)
-SYSCALL(sbrk)
-SYSCALL(sleep)
-SYSCALL(uptime)
-SYSCALL(open)
-SYSCALL(write)
-SYSCALL(mknod)
-SYSCALL(unlink)
-SYSCALL(link)
-SYSCALL(mkdir)
-SYSCALL(close)
-SYSCALL(getch)
-SYSCALL(greeting)
-SYSCALL(shutdown)