fix an incomplete problem

this one was ugly.  Has been made to look better.
Merge branch 'upstream'
import problem sets for Esty Proof Book
Updating sagelet problems

Adding a few new features and also cleaning up things using the current
state of sage.pl.
Iframe embedding
New matrix answer template file

for the subject area templates wiki
Update
Another new matrix answer template file
Update keywords
Add PGcourse.pl
Update MatrixAnswer1.pg
New matrix operations template file
New matrices and custom answer checkers template
Include embedding YouTube videos
New row operations question
New diagonalization problem.
Small fix.
New scaffolding template
Indicate scaffolding.pl as alternate future name
Merge branch 'master' of github.com:drjt/webwork-open-problem-library into drjt-master