Updating to latest NeuroML 2 schema

Using preferred form: ionChannelHH in ion channel example
Removed extra lines
Merge branch 'development' of github.com:NeuralEnsemble/libNeuroML into development
Copying latets version of nml2 schema with minor change
Updating to version 0.2.0
Merge branch 'development'

* development:
  Updating to version 0.2.0
  Copying latets version of nml2 schema with minor change
  Removed extra lines
  Updating to latest NeuroML 2 schema