Add Dozy cheat

[Richard-L]

Add dozy mode for flying and resurrection. Super useful during testing.

Old:
Always useful for testing.

Basically what we know from TR1x:
- Dozy
- Weapons
- Level skip
- Door open

Additionally the TAB key "turbo mode" is also handy (block pushing, ladder climbing), although I'd make it a toggle instead of a step through two speeds for better intuitiveness.

[rr-]

Can we convert this issue into four different issues? It'll be easier to deliver these one-by-one.

[Richard-L]

Sure, done.