Reworked elevators

This is the second publicly available version of the pack. The first one had issues, so that haven't been released here, and WILL NOT BE released in the future either. This version fixed important issues:

• One-way rails had the elevator arrow's texture, which was pointing in the wrong direction
• Elevator displays had the wrong kind of arrow
• Took out some unneeded parts
• Improved overall performance

The pack is very highly detailed, which might cause some PCs to crash when the pack is equipped. I suggest doing a backup before trying the pack out.