updates to pccTables.pl
lots of upgrades to pccTables.pl, which is renamed to niceTables.pl, and pccTables.pl now redirects there
tidying things for develop branch
moved pccTables.pl to OPL/PCC/macros
Update compound problem macros to record which answers are used, so that the iscorrect and canshow options aren't needed.  Add PGML support.  Add documentation.
Fixed the name of the init function (was going to rename this scaffold.pl until I wrote my new versions that I think are even easier to use that these ones).
Use WARN_MESSAGE macro instead of the old WARNING_MESSAGE and WARN
Fix some documentation issues with contextComplexJ.pl
Merge pull request #156 from dpvc/patch-complexJ

Fix some documentation issues with contextComplexJ.pl

- Doc changes - Nothing to test.
Merge pull request #155 from cubranic/warn-message

Use WARN_MESSAGE macro instead of the old WARNING_MESSAGE and WARN

I check that each of the four error messages in PGGraders.pl works now.
Merge pull request #157 from Alex-Jordan/pccTables

Pcc tables

I tested all of the options described in the comment documentation in the macro file.  (Alex's test problem was helpful here.)  Everything seemed to work as advertised.
Merge pull request #154 from dpvc/patch-compoundProblem

Update compound problem macros