Scenario editor

[Trilarion]

Currently there does not seem to be a scenario editor. However, it is desired. With #21 one can simply use a screen similar to the main screen in some God-like mode where one can change anything (terrain, account balances, rails, ...) and then save.

[Trilarion]

It will come after the client is written in JavaFX (depends on #8).

Discussion is necessary whether it should be a special client mode or whether it should be something that locally runs directly on a server with direct access to everything. Both has advantages and disadvantages. Need careful design before.