Move away from walls on evolve

[necessarily-equal]

🎉

[necessarily-equal]

Test procedure:

/team a
/class level0
go to a corner or too close to a wall
/class level4
tada, you sucessfully evolved!

Note that if you go to a corner with things on both side, like in a corner of the alien base in chasm, you may actually not have enough place to evolve: this will not "jump" to allow you to evolve. If you have a corner like this:

\  |
 \ |
  \|

It won't try to "climb". I think those should be corner cases (hehe).

This voluntarily doesn't handle cases where you are under a pipe or similar, and try to evolve anyway.

[slipher]

Great, fixing the inconvenience which was there since Tremulous.

[necessarily-equal]

Ok, I found a bug [EDIT: now fixed].

How to break it:

• open plat23
• go in the corner with the overmind and the egg (the "innermost" part of the base)
• evolve to tyrant

You're then stuck colliding with the egg, and can't move.

[slipher]

Well it looks like the "vertically" function is supposed to make the final decision on whether evolving is allowed, but in the lateral movement case you forgot to actually call it.

[slipher]

Fixes #480 !

[necessarily-equal]

The bug I reported earlier on this PR is now fixed. The code is now a few lines longer but this time I didn't manage to break it 😆

[slipher]

Is it intentional that the stuff fiddling with vertical position is skipped when there is a nonzero lateral displacement?

[necessarily-equal]

Is it intentional that the stuff fiddling with vertical position is skipped when there is a nonzero lateral displacement?

yes, it is: if the lateral displacement finds a spot, then it is known valid. I guess we could push the player towards the ground, but that wouldn't be needed on slopes. So only large steps could benefit from this and it wouldn't be worth it.