Fix ambient sound not updating in game on setting options change

[leoCottret]

Summary

SUMMARY: Bugfixes "Fix ambient volume not updating after options change"

Purpose of change

Fix #2019
Ambient effect volume is not updated after changing it through the options in game.
The volume will only be updated after you move to an other area.
Which can be annoying if you want to test if you like an ambient sound, to adjust the volume etc.

Describe the solution

I first tried to update the volume of the current ambient effect after options change in game (same behavior as music).
But several channels (ambient sounds), can be played simultaneously.
So I now:

• save the last played channel with its options each time a new channel is started
• and on options change
  • stop all channels
  • start the last played channel with its options and the updated volume

Describe alternatives you've considered

I could keep track of every channel parameters to restart every channels on options change, but I feel like it would complexify the code for little gain.
Here the main goals are reached, changing the volume gives instant result, so a player can quickly tweak the ambiant effect volume, and won't think that it's bugged.

Testing

1. Starting the game with 0 ambient sound volume
2. Changing the volume to 100. The ambient effect can be heard
3. Changing the volume to 20. The effect volume is lower, and not duplicated
4. Teleporting to an area with a different effect, changing the volume, the last effect has its volume udpated.

[scarf005]

looks great. tho i suggest to group those variables into struct.