Announcement system refactoring.

Turns announcements into a datum based system to allow a variety of configurations.
Current configuration options include:
Admin logging
Which sound that should play when announced, if any
If the announcement should be stored as a newscast

Request console/standard announcements currently match priority announcements, but have a smaller style/footprint.
Player announcements now include the assignment and name of the person (or the id rather) who made it.

Have currently only updated the request console and all announcements which previously used captain_announce().
Affected automated announcements, such as shuttle messages, should be exactly the same as before.