fix door/bridge IC not working when only two coordinates are used

When people are only using two offsets like it was the case in falsebook (x and y) the bridge will fuck up and set all three coordinates to default instead of using the already set coordinates and only using the one default coordinate.

Example:

[MC1211]
10-0
-1,5:6,4

Current: Will default to 0,1,0 but should be -1,5,0.