Devlog 23.06.20

Changes:

• More sounds! Now picking up powerups, breaking bigger asteroids and taking damage makes a sound.
• Turrets are now also dropped as powerups by dead enemies, and have to be picked up and manually deployed by the player. Default turret deployment key is F. There's no display of number of available turrets at the moment.
• New enemy type: hard asteroid, that becomes temporarily invulnerable on hit, like player's ship.
• Multiple UFOs can now spawn simultaneously, based on the wave number.