AframeRelationConnectorController works

- most functions work
- calculateBorderPosition-function can be universally used to determine the intersection point of a line through two points and an specific object
- no testing of sourceStart/targetEndAtParentBorder due to missing relations in the current model. Should work though with aforementioned function
- no work on circle/square shapes because they don't work correctly in x3dom version
- added a missing semicolon to the original relationConnectorController

Author: Aaron Sillus