Adds a three-second cooldown to the alien hunter pounce

Does as the name implies. I was inspired to make this after a round on Sybil in which one alien hunter knocked down an entire deathsquad. Pounce is still viable, but far less spammy.
So like a pounce leap that knocks people down and a movement leap that doesn't? And the pounce leap has a cooldown but the movement can be spammed?

I see a few potential problems with that. I think that hunters already move fast enough as is; they move faster than a person jacked up on hyperzine. I made this PR to get rid of the "ggnore" status of leaping as is, both for escaping and knocking people over. Escaping is easy enough with the extreme speed that hunters have, and knocking them over is also easy with tacklespam.

In addition, there would be no reason to toggle leap in the three seconds that you have to wait before pouncing again. In fact, in the upcoming commit, it immediately puts you *out* of leap after you land so that you can start doing other actions.

**tl;dr** Making any sort of continuous leaping would probably make hunters more of an issue because then they could move even faster and switch on a whim

Unless I interpreted it wrong, in which case, feel free to correct me.