- Added inverse option to all conditions
- Removed requirement to specify manual truthiness for on_fire, in_air, etc - i.e. removing the requirment to then specify `on_fire: true`, which now defaults to true for all conditions - you can still specify things this way, but the inverse option is preferred

Inverse syntax looks like this:
- id: on_fire
args:
inverse: true

Which will mean that the condition is met when the player is not on fire

- Fixed GUI mask not using the item lookup system