Redo how user activity and status is displayed.

[tlaundal]

Currently a user has three different 'types' of statuses:

• Op, half-op, voiced, etc.
• Active / inactive - This is implemented by subway and is just based on when they last did something in the channel
• Away / available - This is a part of the IRC protocol

Of these only the first two are displayed by subway. The status(op/voiced/etc.) is displayed by prefix, and active/inactive is displayed by the icon. I think this should be redone.

This is how I image it could be done:

• The icon indicates the status(op/half-op/voiced/etc) of the user, this should have a tool-tip text so it is easy to figure out what it means.
• The user name is grayed out on users that are marked as away(IRC protocol)
• Time since last activity in channel for the user can be appended after the user name. Same as it currently is.
  This would, IMHO, be the best way to do it.

Please keep in mind that this issue is not about ordering, but is closely fit with #270.
#307 Implements the graying of the nicknames in a nice way, but is based on subway's concept of active/inactive.