changes for connections
update schema with custom properties and visualreferences for
connections. Remaining work with connections serialization
changes for connection
fix glitch in serializer
Merge remote-tracking branch 'origin/development' into connections
Adding visual group node and element. Serializes new noes.
Merge remote-tracking branch 'origin/neuromlpopulation' into connections
Merge pull request #44 from openworm/connections

Connections
changes quantity to physicalquantity