Kernel+Userland: Addd reboot syscall (#334)

Rolling with the theme of adding a dialog to shutdown the machine, it is
probably nice to have a way to reboot the machine without performing a full
system powerdown.

A reboot program has been added to `/bin/` as well as a corresponding
`syscall` (SC_reboot). This syscall works by attempting to pulse the 8042
keyboard controller. Note that this is NOT supported on  new machines, and
should only be a fallback until we have proper ACPI support.

The implementation causes a triple fault in QEMU, which then restarts the
system. The filesystems are locked and synchronized before this occurs,
so there shouldn't be any corruption etctera.

Userland/reboot.cpp

@@ -0,0 +1,15 @@
+#include <stdio.h>
+#include <unistd.h>
+
+
+int main(int, char**)
+{
+    if (reboot() < 0){
+        perror("reboot");
+        return 1;
+    }
+    return 0;
+}
+
+
+