Add ability to execute commands

[efibs]

Add a setting to specify commands that are executed when events occur.

Events could for example be:

• Pre game started
• Game started
• Game ended
• Player died
• Flag got stolen
• Game ended
• Arena reloaded
• etc...

The config file should be editable from within the game by admins => "Complex Setting DataType". Edit button in settings screen opens edit screen for the complex setting. -> Setting screen is a code editor