Allow free points & paths in cell definitions

[pgleeson]

There has been some interest to re-add the elements for specifying structural information related to a cell as obtained in neuronal reconstructions (e.g. raw data on points along neurites, synapse positions, outlines of cellular/anatomical features).

These elements (free points, paths, polygons, manifolds etc.) had not yet been added to v2 due to low interest in these elements in v1.x.

These could be added to v2.0 in a gradual process by extending the schema, and so be made available in the Java & Python APIs.

Thoughts for priorities for these additions are welcome.

[pgleeson]

Some discussion of this on the NML mailing list here: http://sourceforge.net/p/neuroml/mailman/message/31473740/