niceTables.pl

This pull request needs to be approved at the same time as two related pull requests in libraries and webwork2. The three pull requests do as follows:

In webwork2, certain latex packages are added to hardcopyPreamble.tex
In pg, pccTables.pl is replaced with niceTables.pl, with significant enhancements.
In libraries, several PCC macro files are added, and pccTables.pl redirects to niceTables.pl