Use builtin log from plugin Prelude.so.
Remove unused plugin log.C.
Move sqrt operation to Prelude plugin.
Add truncate, ceiling, floor, and round to Prelude.
Add a list of (integer) triggers to each context.
Add a bool to each reg to mark it as being re-evaluated at invalidation.
Add a method of accessing the triggers from a context object.
Add a plugin and builtin for (trigger i), which adds i to the trigger list.

Here we elect *not* to have the token specified.  Is that a good idea?
Add note.
Merge branch 'master' of github.com:bredelings/BAli-Phy

Conflicts:
	src/Makefile.am
	src/computation/operations.C
	src/computation/operations.H
Add multi-locus sampler for a single theta.