Tesselation Improvements

Added various interpolation methods for radius to avoid mesh
intersection. The methods are:
BNP -> BNP: ease-in-out
BNP->connection/leaf: ease-in
connection/leaf -> BNP: ease-out
connection/leaf -> connection/leaf: linear

one-ring radius of tubes from BNPs aproximated to be half of the
corresponding nodes radius
node radius and node type are new attributes for the node