Spaced Out: Wheel Spacers 22

This update creates more friendly back-end behavior from the mod. It does not change the gameplay aspects. Uninstallation is easier in most cases.

Changelog:

• Changed file layout and extension loading to more closely mimic official content.
• Detect when mod is disabled and delete temporary parts.
• Delete temporary parts on game exit.
• Restored safety of "safe delete" function.
• Stopped exporting some internal functions.