MEDIUM: applets: Don't process more than 200 active applets at once

MEDIUM: applets: Don't process more than 200 active applets at once

Now, we process at most 200 active applets per call to applet_run_active. We use
the same limit as the tasks. With the cache filter and the SPOE, the number of
active applets can now be huge. So, it is important to limit the number of
applets processed in applet_run_active.