Continuing terminal I/O

- Made stdio.h work
- Moved printFiletable back into kernel.c
- TODO: Add stdio.h to all files that should use it (probably next commmit)
- Added some more global addresses. There's a memory layout, but i'm not using it
- Got cursor to be drawn
- Calc program now gets user input

src/stage3.c

@@ -3,7 +3,7 @@
 #include <memory/addresses.h>
 #include <disk/disk.h>
 #include <disk/filesys.h>
-#include <screen/text.h>
+#include <screen/gfxmode.h>
 
 __attribute__ ((section("entry")))
 void main() {