thickness list added, so user can controll the radius/thickness on each level by himself
1) bug fix in orthogonal() 2) all tubes rectangular to bottom plane have the same 'north pol'
orientation of cross connections 'north pole'of same level synchronized
some docu added and some code cleaning done
merge conflict solved
Merge pull request #9 from cpoliwoda/master

thickness list added, so user can controll the radius/thickness on each ...