[Terrain] Angle off-limit spikes in specific cases

[N1ckn1ght]

Example:

Height is limited in between 0 and any number.
Previous angle was slightly bigger than -math.pi * 0.5
Last p2.y is 1
angleDiffLimit slighlty less then math.pi * 0.5
Now terrain generator is stuck because it can't produce such segment so it'd have a limited angle and p2 will be lied in [0;n] boundaries by y.

For now it will just generate an off-limit angle spike. need help to make better gen algorithm.

[N1ckn1ght]

This also may occur on generation of a guaranteed to land on platform.