Loosened the type restrictions on 'nebula::isReady' so that it's
applicable in more settings.
Simplified floppy simulation using 'sim::isReady'.
Nicer whitespace.
Added floppy disk insertion/removal.
Added an option for automatic floppy insertion.
Added a check for multiple floppy disks.
More descriptive logging for ejecting/inserting floppy disks.
Added shortcuts for inserting/ejecting floppy drives.

-- F10: Insert a WP floppy.
-- F11: Insert a floppy.
-- F12: Eject a disk.