#283 Feature/level empty flag reset

[brisbang]

When there is a scripted summon, it will reset the level's cleared status.

Unit testing

• In house of pain, when the first room is cleared, the level is cleared
• When moving into the next room, activating the next group of monsters, the level indicator becomes red once more.
• When playing in nightmare mode, the level is never shown to be unsafe.

[epyon]

This can affect a LOT of shit. I need to take a closer look!