Created the SceneMenu

Created the scene menu with a “start” button that leads to the Scene1,
and two other buttons (for now, useless).
Pause function

Created the pause function, and also included the armour and lives
variables.
Created SpawnManager

Created SpawnManager (yet empty). Also, made some little changes in the
player..
Rearranged paths

Reorganised the scripts paths, separating into the following folders:
Shoots, Player, Enemies and Menu
Cleaning scene1

Deleted some unused objects.
Project update

Some unsaved changes from the last commit.