Implements get_max_rank() in LeApi. Add a fieldtype rank. + A lot of bugfix
The me.json was not up to date (Models don't forward classtypes modifications to loaded json file)
Some bugfix on fieldtypes that was not used (because of old me.json)
Added default fields for EmClass + fixing some tests and EmClass function that were broken
Added default fields for EmClass, they are listed by classtype in EmClassType
Fixing some tests (testing that a new EmClass has no fieldgroups)
Fixing the delete_check of EmClass. Now an EmClass can be deleted if it contains only default fieldgroup and default fields