neuronvisio 0.5.1 release

[Michele Mattioni]

Dear all,

this is just a minor bugfix release for Neuronvisio:
http://mattions.github.com/neuronvisio

From the Changes:
* Fixed the picking of the cylinder. Possible to select a cylinder
clicking anywhere.
* Possibility to plot points instead of a lines
* BaseRef class are discriminated through the group id and not any
more on class base.

Point one should make your life easier when trying to pick a section,
point two is useful if you want to plot the points, instead of having
a line.

Last bit is about the HDF5 structured file used to save the model and
the computational results. The different group are discriminated by
the group_id, so you can avoid to subclass if you don't want too.

Have fun,
Michele.