Added new Python connections - now there is a central library of new connection types and these appear in the connection menu. Additionally python scripts are stored in the metaData.xml file and the genrated conenctivity in the model.xml file. This allows spineCreator to load the connectivity instead of having to generate it anew. Additioanlly the model.xml file becomes a pure SpineML file (with the addition of binary file syntax), which is betetr for sharing with other tools. TODO - it has just occured thet connections are not forced to regenerate before writing out. Only the Kernel conneciton type exists that breaks SpineML purity in the model.xml file - as I currently need it! It will be removed once I migrate to a Python way of doing Convolution Kernels
Added code to check if python connections have been altered before the connectivity is saved, that way it can be assumed that all loaded connectivity is up-to-date
Tidying up a few items with the python connection generation and switching of undostacks for components
Merge branch 'new_python_connections'