Merge pull request #44 from mlosch/master

distinguish between on node and merge threshold. shortest path to start node
Merge pull request #45 from mlosch/master

fix naming
Merge pull request #46 from mlosch/master

fix circle draw bug
Merge pull request #47 from mlosch/master

fix out of bounds exception
Merge pull request #48 from mlosch/master

always connect nodes, when place_node is called.
Merge pull request #49 from mlosch/master

make sure we only merge object nodes when they both have an object
m3 brain
Merge remote-tracking branch 'upstream/master'
use new edge array instead of id_north etc.