Added sdli_definitions for data types and typedefs/usings
Introducing inputcontext, stack-implemented method of managing context-based behaviour (enter QTE? -> push pre-generated context)
Updated sample
Updated readme
Added callback basic interface
    Callbacks are lambdas/void() functions added to a list an are fired on dispatch
    Callback can listen to onPress(, onRelease, isDown, isUp)
    Planned: Axes can also use callbacks with Analog_GT or Analog_LT and a value
    Callbacks are added to a context and are only valid in the active context