Vehicles don't collide flat terrain even when it's bashable.

The flat terrain check is based on the movecost being 2 (e.g. floor).
Fix display bugs in editmap:

Check furniture/terrain count module available width, previous code used the wrong value for this modulo check.

Correct width of furniture/terrain list calculation, note that the loop starts at x = 3 and goes to x = pickw, so there are pickw - 3 items per line,
this means the number of lines must be calculated based on pickw - 3.

Removes num_terrain_types and num_furniture_types, instead use terlist.size() / furnlist.size() directly, what's the point of storing those numbers separately when the vector already contains them?
Merge pull request #8951 from BevapDin/fix-vehicle-dragging

Fix vehicle dragging