Return "tick on input" option

[TheRealKaup]

At one point, one could create a game loop that would continue to the next tick after Input::Get() would return. Currently, that is not an option, as:

• A) Input::Get() is a private and static member function.
• B) Most of Get()'s functionality has been moved to Input::Loop().

Also find a way to integrate it alongside invocations.

An alternative would be "render on demand" - only when things change, that could be when the tick had input or invocations.

This is a dependency for TextureCreator.

[TheRealKaup]

// ... in game loop
if (engine.time.invokedThisTick && engine.input.inputThisTick)
{
    ui.Render();
    engine.output.Draw(ui.image);
    engine.output.Print();
}
// ...