[PEAK] @action rules in Trellis SVN

[Phillip J. Eby]

Okay, I've overhauled the Trellis' handling of rules that modify 
other cells; you now have to explicitly mark a rule as a 
@trellis.action in order to be allowed to change cells or invoke 
@modifier functions or methods.

@action rules can't be read by any other rules; they are effectively 
run in bulk at the (logical) end of a recalculation.

The tutorial has been modified a fair bit since last week, so if 
you've read it already, you should definitely review the changes 
using either of these URLs:

http://peak.telecommunity.com/DevCenter/Trellis?action=diff&date=1185993742

http://svn.eby-sarna.com/Trellis/README.txt?rev=2380&r1=2379&r2=2380

There are still more changes in the works, including a revamp of how 
the "task" mechanism works, and changing the repr() of cells to not 
have side effects.  I may also work on the priority heap and/or 
listener optimizations I posted about yesterday.

Once these things are done, I'll work on finishing the documentation 
for the 0.5b1 release, which seems to be on track for being completed this week.