Separate accurate an inaccurate directions
Velocity could be multiplied and divided by a number
Use the Velocity class in Core::ParallaxBackground

Also I find it necessary to provide information about the distance
between the front and the rear scene even though it may end up unused.
Require Velocity in utils
Use velocity to combine direction and speed in Core::LoopingScene
Fix Vec2D#magnitude= when #magnitude == 0
Add ways of changing the speed and direction/angle of velocity
Add а more convenient way of creating Velocity instances
Update Core::Bullet using the Velocity class
Change Core::Bullet initializer so only type and direction are needed
Update Core::Spaceship so it uses the Utils::Velocity class
Add type attribute readers to the bullet and spaceship classes

This way we can easily get the visual representation we need, when
writing the gui/cli.
Update Renderers::Bullet so it works after all the changes
Update the resource names so they match the new types
Add the tile size of the falcon resource so it can be loaded
Update Renderers::Spaceship so it works after all changes in core
Remove constants from Core

They should either not exist or at least be moved somewhere else.
Make things work for now
Add first thoughts for the Utils::Direction class
Switch the directions, 0-360 degrees is forward - left - back - right