SFX Update + Steam bug fix!

Two updates for the system today, one small feature update and one small bug fix.

Bug fix

On Steam, achievements which have a progress stat where stat_modulo wasn't set can throw an error when updating progress. This only happens on Steam - big thank you to Made Marion's tester Bex for discovering this issue!

Do I need to update?

• If your game is not on Steam, no. 
• If your game is on Steam but you don't use progress stats for your achievements, no. 
• If your game is on Steam and uses progress stats for achievements but supplies a stat_modulo which is not equal to zero, no. 
• Otherwise, yes. And yes if you're planning on including progress stats on Steam without supplying a stat_modulo also.

Feature

Thank you to the suggestion by Wudgeous in a lovely post on the forums, I've added a configuration value so you can cause a sound effect to play when the achievement popup appers. The instructions on how to do so have been added to the README. You can also change which channel it plays on; by default, it uses the audio channel to play the sound.

As per usual, if you'd like to see the exact changes, head over to the history on GitHub.