This commit changes the former callback based design to handle key input
(GLFW-like) to an event loop based design (SDL-like). This uses a
TailQueue to store the events from inside of standard glfw callbacks.
This Queue is then popped while polling, thereby emulating event loop.
Removes from Engine the function: ``setKeyCallback`` and adds the
function: ``pollEvent`` which may return an event or null.
This change was done for two reasons:
1) Removing dependence of Engine on App. This was a circular dependency
and a genuine bad design.
2) Solve the recent regression due to the same which was (i) preventing
using types declared in Engine.zig and (ii) preventing usage of
multiple source files in an application.
Currently only key press and release events are implemented as these are
the ones currently used in examples.
This Timer uses std.time.Timer as backing timer in native platforms, and
will use custom timers for special platforms (wasm, android?, ios?).
Unlike std.time.Timer, its primary API is focused on floats. Also meant
to provides some convenient functions alongside base ones.
Follows std.time.Timer API, but methods by default return f32 i.e
non-precise variant with precise variants available returning u64.
