Remaining physics issues from DireKrow's posts

[namida]

Copy/pasted from Discord for reference here. Based on the 0.0.8.0 release build (or more specifically, the commit immediately after it that only changes the version number).

- Blockers at the top of slopes are ignored by lemmings walking up the slope. Turners work.
- If a second builder starts building in the same place as a previous builder, they'll build an overlapping bridge. In L3D, they give up after one tile.
- If a walker encounters a stack of builder tiles, they'll be boosted up to the top of them. Happens in L3D too.
- If a builder builds into any existing builder bridge tiles, they'll be boosted up on top of them and continuing building uninterrupted. Happens in L3D, but causes them to give up.
- If a builder is mid-build and mid-block, assigning them as a blocker/turner will interrupt their build and make them into a walker. In L3D it doesn't let you do this.

[DireKrow]

- Climbers sliding on ice currently don't climb when they encounter a wall. They should.

[namida]

- If a walker encounters a stack of builder tiles, they'll be boosted up to the top of them. Happens in L3D too.

After some thought, I think leaving this as-is is the correct approach.

Lemmings can step up that height any time such a height step (without a wall blocking it) is in front of them anyway - it's a 16:1 gradient, the highest they can step up in any situation, exactly. A stack of builder bricks is basically giving them such a setup every frame - this is indeed what happens; they don't jump directly to the top but rather step up one step each frame. The weirdness only arises because unlike anything else, builder bricks are only treated as solid in some situations, and the exact combination of which are / aren't leads to this outcome.

Also, becuase this would be a MAJOR pain in the ass to actually block, for little benefit.

With that, I believe all the issues noted in this topic are sorted.