Various minor level adjustments

• This one's easy! - Make the hitbox on the first exit smaller so it's easier to get over with a single ladder
• Step by step! - Move the start button so players don't get stuck trying to jump up when Nummels are walking over the gap and getting in the way
• Dig it! - Add some rocks to prevent players from digging under the exit area
• Watch that first step! - Make it safer for Nummels to walk into the underground area, and split the ladder so it's easier to get out of the hole on the left
• They call me Mr. Squishy Face! - Make it easier to get up to the top area by wall sticking on the left side
• Nummels stay right! - Move the ladders on the far left so they are easier to spot (some players didn't see them way over there)
• Numminko! - Make it so the Nummels don't walk back to the springboard after they fall and are launched over
• Hidey hole! - Make it more clear that you can get out of the left side of the level after all Nummels are saved
• They have electric skin! - Fix the coin that was in the wall, adjust the block on the left side to make it easier to jump on
• Step down! - Add rocks so you can't get to the challenge coins without doing the challenge