first run at per-visualization timeouts, as per the design worked out on panel-devel.
i'm sure there are several bugs at this point (so don't try and use it quite yet ;) but most importantly:

- all methods are implemented
- it compiles ;)
- it does not have any negative impact on existing engines and applets as they currently are written

next will be to put it all through its paces, starting with the time engine and analog clock applet. i may not get to that until tomorrow, hoever.

this commit also fixed a number of buglettes along the way that had creeped in, e.g. not properly connecting all signals in connectAllSources (moved that ccode to the Private class to avoid code dupe and similar bugs in the future)