Move Event definition to EventManager.cpp
Fix memory leak in MenuHUDLog
Don't allow Events to maintain their own StatBlock

Instead, StatBlocks that are used by events are stored in a vector in
the Map class. This way, the StatBlocks will stay alive during the life
of Hazards that they might spawn. Also, this means no worrying about
deep copying the StatBlock when Events get copied.

Fixes #122
Fixes #1197
Add bounds check to PowerManager::activate()
Merge pull request #1198 from dorkster/fixes

Segfault fixes