sf::RectangleShapes were created brand new each frame, which takes a lot of time.
Instead, keep an array of them available and update them instead of creating new ones.
This also allows a nice optimization of only updating them if needed, by checking their
previous value.
Update the available number of rects when the window resizes.
SFML and Dear ImGui have incompatible color types, abstract them through
a new Color class which has conversions.
Centralize color constants in a namespace as well.
Previously CastRay did the scale computation and used the player view statistics.
This makes it quite specialized, and the rest of the computations are made outside.
Move the computations in the render function and make castRay generic.
World has a lot of type conversion warnings. Take care of most of them,
for a slight performance hit ( :( ).
Re-order constructor parameters to match declaration.
Move FillColumn to a more appropriate place.
GetBlock gets called a lot : use direct memory access of the vector
rather than going through bounds checks with .at().
Introduce an integer overload to remove warnings.
Player: Add rotation and linear speeds, as well as their current state.
Player: Allow to move in the local coordinates and compute
world-speed equivalent.
Player: Update movement axis while rotating.
World: Add a function to advance a step.
Main: Handle key events, add world step in the main loop.
Implement the basic raycaster, checking every block intersection and the block
linked to that position.
Split the screen uniformally along the width.
Add data needed for camera maths in the Player class
Specify constraints on the raycast parameters.
Render the screen using the raycasts.
Call the renderer in the main loop.
