Lots of hacking:

- Turn Keyboard into a CharacterDevice (85,1) at /dev/keyboard.
- Implement MM::unmapRegionsForTask() and MM::unmapRegion()
- Save SS correctly on interrupt.
- Add a simple Spawn syscall for launching another process.
- Move a bunch of IO syscall debug output behind DEBUG_IO.
- Have ASSERT do a "cli" immediately when failing.
  This makes the output look proper every time.
- Implement a bunch of syscalls in LibC.
- Add a simple shell ("sh"). All it can do now is read a line
  of text from /dev/keyboard and then try launching the specified
  executable by calling spawn().

There are definitely bugs in here, but we're moving on forward.

LibC/types.h

@@ -6,9 +6,16 @@ typedef unsigned int dword;
 typedef unsigned short word;
 typedef unsigned char byte;
 
+typedef signed int signed_dword;
+typedef signed short signed_word;
+typedef signed char signed_byte;
+
 typedef dword uid_t;
 typedef dword gid_t;
 typedef dword pid_t;
 
+typedef dword size_t;
+typedef signed_dword ssize_t;
+
 }