Add folding bicycle to a few spawn groups.
Add construction recipe for folding bicycle.
Drop folding bicycle box items on ground when folding bicycle.
Set minimum number of turns between autosave to 1 to prevent div/0 error. Fixes #1922.
Serialize flags and passenger_id members of vehicle components.
Allow saving while in a vehicle. Fixes #2064
Merge PR #2077 - Folding bike improvements
Merge PR #2080 - Vehicle saving
Merge PR #2078 - Autosave option fix