Add `flying_mode` player preference to database
Tidy
Add `travel.manual_flight_delay` config option
Consolidate duplicate methods
Add `/tardisprefs flight [mode]1 command

Where `[mode]` is one of normal, regulator, manual
Deny over world monster spawns in Nether and End
First attempt at implementing flight modes

For manual flight mode I think the repeaters are:
world: Helmic Regulator
x: Astrosextant Rectifier
z: Gravitic Anomaliser
y: Absolute Tesseractulator
A visual effect has been added to help :)