Added the ability to stitch two networks together.  This uses Delaunay tessellation and requires the networks be positioned corrrectly in space first.
- The method is underscored since it will surely evolve under development
Added the ability to send a list of labels to apply to new pores when 'extending' the network
Bug fix in stitch, the shape of the adjacency matrix was count wrong
Adjusted 'stitch' to accept a list of pores to stitch rather than two labels.  Also added the existing labels in the doner network to the recipient's labels by default, and 'stitched' to the new throats generated by the method.
Added options to 'stitch'
- now user can specifiy delaunay or nearest for connection (not much difference)
- can also specify the maximum allowed throat length...this is a very useful improvement