[click] run_scheduled() deprecated, use run_task()/run_timer()

[Eddie Kohler]

Hi all,

We're in the process of revamping Click's task structure, in particular to
allow kernel Click to share the CPU more effectively with other processes.

I just checked in the first part of the change. DO NOT use the
run_scheduled() function any more, it has been deprecated! Instead, use one
of these functions:

   for Tasks:		bool run_task();
   for Timers:		void run_timer();

The bool return value of run_task() represents whether or not the task
managed to do any useful work. (For example, sending a packet.) The
scheduling loop will eventually pay attention to these return values, and
use less CPU time when few of the tasks are doing useful work.

I've updated all of the elements in the repository to use run_task() or
run_timer(). However, run_scheduled() will still work if you don't feel
like updating right away.

This work was done largely by Petros Zerfos, thanks Petros!!

Eddie