This commit adds the MotD model for storing and retrieving
messages-of-the-day.
It also adds a model for messages. Messages have an author as well as a
thread they belong to, the thread can be read by a specific number of
authors. FUrthermore, the message model supports system messages.
This commit introduces a number of needed changes:
- Character is now implementing the CharacterInterface
- MissingCharacter and SystemCharacter are supporting "pseudo-characters"
- trait MockCharacter implements non-implemented methods for
MissingCharacter and SytemCharacter
- Characters are now soft-deletable. Models wanting to load soft-deleted
characters need to fetch them eagerly.
Closes#17
Vassyli