A bit more elegant dealing with problems with the connection to provoviz
Clear dataset function
Tick-aware entity adding (will introduce a prov:wasDerivedFrom relation if the variable existed previously)
Now using the ticker-aware entity builder... which should give us more connections between variable versions (prov:wasDerivedFrom)
Commented standard procedure to clear the provenance dataset at every (re)load of the extension.
Only adding variables to input if they were not 'None'
Using logger instead of print outputs
No longer checking for empty variables, as this did not really work all that well.