Minor Audio Inconvenience

Major Changes:

• The mod now supports NeoForge.
• The versions are now suffixed with their respective mod loader. (i.e. 0.1.0-fabric, 0.1.0-neoforge)

Changes:

• use SoundManager.getKeys method instead of making the sounds map available through the access widener (1b50ac3)
• replace Optional<float> arguments null -> Optional.empty (3bff8f5)