Major Updates to Spinny Plane

Hi everyone. Based on a lot of feedback I received during the Kenney Jam 2021 I have made some pretty significant updates to Spinny Plane! Let me know what you think!

Change log:

• Replace limited inventory with unlimited ammo with a cooldown. Added a cooldown indicator in the top left corner. 
• Added a round time limit of 30 seconds. (may increase time later)
  • Time can be added by reaching certain point amounts (currently 100, 300, 600, 1200 points). A message appears and a notification sound is played when time is added.
• Enemies now spawn whenever an enemy leaves the screen, not just when an enemy is destroyed.
• Button sound effects, menu theme, and main background music added.

To do/Bug/Wish List:

• High score does not save when played in browser. 
• May add new enemy types (a quicker enemy that is worth more points?)
• May add upgrades to bullets (bouncy bullets?)
• May add boss battle which takes several crashes to kill but may block attacks.