Added support for sounds.
Sound and music buttons in options GUI now work.
Bug fixed where reopening the window/app for the game would resume the game when it should still be paused.
Swarmlings no longer get stuck together.
Fire arrows now light enemies on fire 100% of the time.
In the upgrade GUI, cost is now colored red if the item can't be afforded.
In the upgrade GUI, buttons are only greyed out if they are fully upgraded, not if they can't be afforded.
Updated credits.