GUI: Use Domain::const_iterator in EventRecorder code when possible.
COMMON: Do not let ConfigManager::Domain inherit from StringMap.

Instead we provide wrapper functionality now. Intuitively a Domain is not a
simple StringMap.
COMMON: Get rid of write version of ConfigManager::getGameDomains.

This can be abused to insert Domains into the game domains without any checks.
Instead, only write iterator access is given.
Merge pull request #377 from lordhoto/config-manager-cleanup

Config Manager Cleanup