When looking up templates by name and name isn't found, return

When looking up templates by name and name isn't found, return
first template instead of NULL (suggested by Wayne Schuller <k_wayne@linuxpower.org>).  In addition, added code to register templates (make known, if not already known) when they are encountered when reading a label.

git-svn-id: https://glabels.svn.sourceforge.net/svnroot/glabels/trunk@386 f5e0f49d-192f-0410-a22d-a8d8700d0965