Lots of small quality improvements and even got most of the core task
functionality online, although currently a slight reorganization of the
TaskStatus object tree has things broken.

-Peter Mawhorter
Fixed a regression in build_schema due to the change in Predicate args
from a list to a tuple. Also fixed breakage in tasknet due to the
restructuring of the TaskStatus structure.

-Peter Mawhorter
All tests pass *and* the main.py functionality is working (up to the
point where some of the tasks are not yet defined). This means that
basic parser and tasknet functionality is in place.

-Peter Mawhorter
A bunch of work in different directions, working towards both a coherent
simulation model and a coherent task authoring language. Things are
partial and broken at the moment.

-Peter Mawhorter