[x] Remove functions that are not used and that can be achieved using other functions
[x] allow_input("WORLD") should be changed into a layer system, where each layer says whether they "request capture" of mouse/keyboard, and then a higher level system decides which layer gets the input, and provides a is_input_allowed() for each layer, as some layers have higher level than others and will take priority.
[x] Review the "immediate" mode API and see if we can switch to full event-based
allow_input("WORLD")should be changed into a layer system, where each layer says whether they "request capture" of mouse/keyboard, and then a higher level system decides which layer gets the input, and provides ais_input_allowed()for each layer, as some layers have higher level than others and will take priority.