Revision 2698

Add better error reporting in PG translator.  In particular, these
changes add two new features:

	1)  produce a full stack trace when a .pg file dies, and
	2)  convert (eval nnn) references to filenames, when
	    possible, in warn and die messages while processing a
	    .pg file.

There is also a change in the webwork tree that is needed to make this
all work, so be sure to apply updates in both trees.