Add sound effects

[jmespadero]

Add sound effects as monster attack, jumps, fire sound, owls, etc...
As done with textures, ensure every sound has a open license and trace the origin of the files.

For example, a good start point is:
https://freesound.org/browse/tags/sound-effects/
https://www.audioblocks.com/royalty-free-audio/sound-effects

And for other royalty-free audios (music, etc)
https://freesound.org
https://www.audioblocks.com/royalty-free-audio/

[jmespadero]

A nice sample of walk on a gravel path...
https://freesound.org/people/tec%20studios/sounds/98491/

A bell (could be used for the #1 temple)
https://freesound.org/people/Toivo161/sounds/266007/