Merge pull request #2 from cgrevisse/master

Sync
Merge pull request #3 from cgrevisse/master

Update
Add default value for comment attribute
Add (MineGui) XML import feature
Update views.py
Adapt code such that onotolgies are taken into account
Changing attribute from bool to string

Got some weird Integrity Errors
Merge pull request #20 from rsirres/master

Add XML import feature