[Feature #11] StarField class created.

It generate stars.
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[Feature #11] StarField added on title screen.
Merge branch 'feature/11-title-screen-stars' into develop
[Feature #3] When on game over screen, any key pressed opens the menu.
[Feature #3] Resume button removed from game over screen.
[Feature #3] Pad controller now also opens game over menu on any key.
Merge branch 'develop' of github.com:aurelien-defossez/soviet-vs-asteroids into develop
[Feature #3] Fix: Start does not close the game over menu, and shop music is not played on this menu
Merge branch 'feature/3-game-over-menu' into develop
Merge remote-tracking branch 'origin/develop' into develop
[Feature #3] "Game Over" text stays in the background when opening game over menu.
[Feature #13] Game over text stomps the screen and makes it shake.
[Fix] It was not possible to buy un upgrade if the player had the exact amount of roubles.
[Feature #12] Missile explosion sprite added.
[Feature #12] Missile explosion size depends on asteroid size
[Fix] Game over animation is played even if the player opens the menu immediately.
[Useless] Starting position of player arms follow the static sprite arms.
[Feature Max Resolution] Window is now at the same resolution as the user desktop main screen.
[Feature Max Resolution] GUI updated to follow new dynamic resolution.