Add sideways icecrushers

[weluvgoatz]

This adds an option for the icecrusher to go sideways instead of up and down, and this can be activated if the player is in the line of sight or stands on top of the icecrusher and gets in the direction he wants to be launched. The code quality of this might be poor, which I will fix, but please bugtest and see if everything works alright. If so, hopefully this can be merged.

[Zwatotem]

I spotted three things right away:

1. Icecrushers placed right by the wall (with snapping in editor) won't ever get back to their original position (pixel precision bug): https://youtu.be/fHaZs-AmkqY
2. Not really a bug, but probably unintended behavior; icecrushers keep going back when Tux just chills on top of them: https://youtu.be/dDZwa4xy_6c
3. Unlike topdown crushers you don't die upon touching the crushing side (no video)

[weluvgoatz]

I've added a commit to hopefully make this build and fix that first bug you listed. However, the other 2 things you listed are very much intentional behavior.

[divVerent]

On the one hand, I really hate them with a passion. Sideways crushers make for bad and surprising gameplay, and they got quite a bad track record in a certain other game with a level editor. Their only purpose ever is for trolling - anything else is better done with a platform. What's next, suddenly attaching little parachutes to them making them instantly slow down, for even more trolling?

On the other hand: making a sideways ice crusher in a troll level took me only this much code:

    (scriptedobject
      (name "juzkrosh")
      (sprite "/images/creatures/icecrusher/krosh.sprite")
      (x 2176)
      (y 416)
    )
    (ispy
      (script "juzkrosh.set_velocity(-500, 0)
wait(1)
juzkrosh.set_velocity(200, 0)")
      (facing-down #t)
      (direction "down")
      (x 2048)
      (y 384)
    )

Given this, the cost of not providing them, despite them being that simple to make anyway, is that level creators who want them anyway will do so using nonstandard means. If they must exist, it's probably better to standardize their gameplay, including sensitivity to player, crushing speed, etc, rather than every level using them having somewhat different parameters on them.