Various Iron hatch improvements

[Quinteger]

This PR contains a few improvements to the iron hatch. The initial idea was to add the same speed-up mechanic which is present on metal rung ladders, but I took opportunity to add a few extra things. The complete changelist is as follows:

• Open iron hatches now provide the same speed boost as ladders
• Hatch shape was modified in both states:
  • Open hatch is now 3 pixels thick, which matches both your and vanilla ladders, reducing the risk of being stuck on an invisible edge; the horizontal rim is now also part of the shape
  • Closed hatch now covers the entire block, which allowed to implement sunlight blocking
• The suction mechanic of the hatch was weakened a bit (from 0.3 to 0.2), as it tended to overshoot and made you bump upwards, as if you're about to climb the opposite side of the block, which was a bit annoying
• Suction is disabled when crouching
• A bit of refactoring

[stfwi]

Hi Sergii, veri nice, let me pull this in, I may do some minor changes down the road, but on the hub diff here it looks pretty good already. Cheers.-