New scheduler and interruptible blocking.

A new scheduler replaces the old one.
  - There are no sched_xxx_notify() calls that ask scheduler to change task state.
  - Tasks now have priorities and different timeslices.
  - One second interval is distributed among processes.
  - There are just runnable and expired queues.
  - SCHED_GRANULARITY determines a maximum running boundary for tasks.
  - Scheduler can now detect a safe point and suspend a task.

Interruptible blocking is implemented.
  - Mutexes, waitqueues and ipc are modified to have an interruptible nature.
  - Sleep information is stored on the ktcb. (which waitqueue? etc.)

include/l4/lib/math.h

@@ -2,5 +2,6 @@
 #define __LIB_MATH_H__
 
 #define min(x, y)		(((x) < (y)) ? x : y)
+#define max(x, y)		(((x) > (y)) ? x : y)
 
 #endif /* __LIB_MATH_H__ */