Updates to get plugin loading in 2.4
First revision of plugin. Removes all support for styling from plugin

Now the plugin is solely used to save a colour index value to an
attribute in the layer. Users should set up their own classified
rendering based on this attribute.
Also add unconnected features to graph
Add improved colouring algorithm

This algorithm improves on the random algorithm by:
- selecting features to colour based on larger number of neighbours
first
- selecting colours for features with an attempt to balance to
total number of features in each colour
Remove unused files