Add support for Dymo labels in breeding plugin.

(Done in evil hackmode for now, code needs to be cleaned and merged with
cagelabel plugin).
Move nr of columns parameter from constructor to template.
Ipdate label plugin to new labelgenerator backend format.
Add some sensible default measurements to show in matrix.
- Tweaks for dymo label layout, optimize for type 99014, 101mm x 54mm.
- Remove some debugging statements.