done when the molecule viewer is requested. Important as we don't
  want all of Kalzium to depend on QtOpenGL. Thanks to Carsten and
  the Dashboard.
- fix memleak: unless I'm mistaken, the old molecule wasn't deleted
  when a new one is loaded. Avogadro (the app) calls deleteLater() on the old
  molecule. Now we do the same.


svn path=/trunk/KDE/kdeedu/kalzium/; revision=794818