Level Creator Update

Changelog for the level creator:

- Added the Camera Hint property to Jack, which toggles the visibility of the rectangle that shows what the player could see if they were playing your level.

- Added the Walk property to enemies, which shows if they're an enemy that walks all the time or if they stand still until they see you (or just to make cool still-scenes).

- Made doors darken when opened (as they do in the game).

- Fixed a glitch where if you set the snap to a value other than 8 pixels (full tile) then switched to placing tiles, the visual grid would not work properly (due to wrong variables).

- Fixed a glitch where the visual grid could become offset by half the snap on both axes (due to the two wrong variables left over from the previous fix).