Duke3D: make pipebombs, morter and bouncemine ignore blocking lines

This is a less conservative MR than usual, and it stems from issue #154.

What happened in that issue is that, due to optimizations made to updatesectorz (breadth-first search), a side-effect emerged in which pipebombs are no longer able to cross two blocking lines if thrown at close range. Now the first line is passed, but it gets stuck at the second. This breaks map progression in Red 4.

Considering that the original behavior is a glitch, and that attempting to fix this in the Build source is probably incredibly tedious, I suggest that the easiest way to resolve the problem is to make pipebombs ignore the blocking bit on walls.

I think it makes sense to do so even outside of this context. The pipebomb is the only player projectile that gets stuck on invisible blocking walls. Changing this would make its behavior more consistent with other weapons. Furthermore, the potential to break anything is very low, as I can't imagine that any maps specifically relied on this property. I also applied the change for the Battlelord's mortar, as it also acts like a projectile. And since bouncemine doesn't move, I believe the change doesn't affect it at all.

Fixes #154