Stable release of 0.8.8

https://foundryvtt.com/releases/0.8.8

Adds new FOUNDRY_DEMO_CONFIG environment variable for configuring demo mode.

⚠️ WARNING

WARNING: Version 0.8.8 is labeled as a stable release, but there is always the possibility of unexpected bugs or module compatibility issues. We do not recommend updating immediately prior to a game session unless you are confident in your own ability to troubleshoot any issues that arise.