Always follow the zone order from the page template configuration in the page admin.

Missing zones are no longer added to the bottom but in place.
"rows" and "cols" template configuration parameters are now included 
for existing zones..
Enforce page admin layout conforming to "cols" by using fixed table layout.
Refactor edit tab data into separate methods per tab and clean-up naming.
Increase method visibility and add PHP docs
Merge pull request #168 from bvleur/fix-page-admin-layout

Fix page admin layout