-Fixed a bug where I was referencing an unused, old class combo box
instead of my own by mistake (resulted in crash when loading problem set
with recentClass saved in it).
-Having an incorrect problem set path no longer spits out stack trace
and errors, just prints to standard output that it was not loaded.
-Fixed a bug where the recentClass or recentFeat not present in the Prop
file was not caught or handled properly.