Updated test0 with a forktest. Fixed timeslices. Updated kmem usage calculations.

- test0 now forks 16 tasks that each modify a global variable.
- scheduler now gives 1/10th of a second per task. It also does not increase timeslice
  of a task that has scheduled.
- When a memory is granted to the kernel, the distribution of this memory to memcaches
  was calculated in a complicated way. This is now simplified.

src/api/ipc.c

@@ -242,11 +242,11 @@ int sys_ipc(syscall_context_t *regs)
 	int ret = 0;
 
 	/* Check arguments */
-	if (!((from >= L4_ANYTHREAD) && (from <= MAX_PREDEFINED_TID))) {
+	if (from < L4_ANYTHREAD) {
 		ret = -EINVAL;
 		goto error;
 	}
-	if (!((to >= L4_ANYTHREAD) && (to <= MAX_PREDEFINED_TID))) {
+	if (to < L4_ANYTHREAD) {
 		ret = -EINVAL;
 		goto error;
 	}