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

shutdown.sym

@@ -1,48 +0,0 @@
-00000000 shutdown.c
-00000000 ulib.c
-00000000 printf.c
-000003a0 printint
-000007fc digits.0
-00000000 umalloc.c
-00000ab0 freep
-00000ab4 base
-00000090 strcpy
-00000450 printf
-0000038b greeting
-000002b0 memmove
-0000035b mknod
-000001b0 gets
-0000032b getpid
-00000680 malloc
-0000033b sleep
-000002f3 pipe
-00000383 getch
-00000353 write
-00000313 fstat
-00000303 kill
-0000031b chdir
-0000030b exec
-000002eb wait
-000002fb read
-00000363 unlink
-000002db fork
-00000333 sbrk
-00000343 uptime
-00000ab0 __bss_start
-00000150 memset
-00000000 main
-000000c0 strcmp
-00000393 shutdown
-00000323 dup
-00000220 stat
-00000ab0 _edata
-00000abc _end
-0000036b link
-000002e3 exit
-00000270 atoi
-00000120 strlen
-0000034b open
-00000170 strchr
-00000373 mkdir
-0000037b close
-000005f0 free