added strict checkpoints

If enabled maps can be build where the ways can cross without cheating.
Also one is able to build (short) race maps with more then one lap to win.

__note:__ I'm not sure why here was -2as default, but with -1 I didn't recognized a difference with and without teams. 
https://github.com/XXLTomate/XXLDDRace/commit/a25bc58b778468384d95b53a4d6351db5f7b6d24#L3L1268
https://github.com/XXLTomate/XXLDDRace/commit/a25bc58b778468384d95b53a4d6351db5f7b6d24#L4L345