Because of fucking numerical instability, updating the UI's input values
every frame caused problems. Fixed this by making sure it's set only if
the override is disabled or at the first frame after it is enabled.
Camera control using the input overrides panel works, although the
controls are a bit too sensitive (and there's a risk of fucking things
up with bad Up vectors)
+ Basic structures
+ Partial implementation in the sync manager
+ Partial implementation of the single float override
+ Silly hardcoded tests in the demo/main files
