Distinguish between the global viewspace and a view group

[mvanderkamp]

Differentiates between the Viewspace (a new class) and ServerViewGroups. This allows the creation of groups that are only a subset of the total number of views.

• The layouts don't yet support this. I think we need to incorporate layouts into ServerViewGroups and also have the ServerViewGroups or something similar track devices. Perhaps the view should know it's associated device.
• The related code and concepts may still need some iteration.

Includes a bit of cleanup to help with this:

• Rename ServerGroup -> ServerItemGroup
• Rename createGroup -> createItemGroup
• Attach settings to the Application instead of the workspace
• Store fewer references to the workspace
• Use application.emit directly instead of messageHandler.send
• Store fewer references to the MessageHandler
• Don't pass workspace into message handler separately
• Only pass the client limit, not all settings, to the switchboard
• Document more settings
• Fix formatting
• Sort and add warnings to settings
• Fix bug from not using this. before settings - missed default
• Remove commented-out line

Closes #62