Added TableTools. Added export for CSV and PDF to measurement table
Fix export widget - export NetworkX json graph

Uses the set of neurons in the selection table, and now reuses
the same, fast backend-function that is used for the graph widget.
Additional comment to store graphml file
Retrieve number of reviewed nodes in export
Confidence threshold and bandwith as optional parameter
Added reviewed count and N-order retrieval
Replace GET by POST requests
Enable creation of simultaneous, independent connectivity widgets