Fix null-tv bug
Exterminate truth value factory.

1) factories are a fundamentally bad programming pattern in any
   code that is not about serialization (where they are fundamental).

2) these factories were used only in Saving-Loading, which is where
   things got moved.

3) SavingLoading is just about entirely obsolete anyway.
Resume work on the main task.

The previous three dozen commits were a giant distracton...
Add notes about command-line processing.
Start moving common code into the generic shell
Make evaluators inherit from a common base class
Make more of the evaluators generic.
Migrate more code into the genereic shell
Move more code to generic shell
iMove the last of the code into the generic shell
Generic shell should be non-denominational
Save partial work.
Move method from header to c file
Assorted minor updates.

Final working version. Phew ...
Merge pull request #435 from linas/master

Assorted cleanup, development.