Changed eval() calls to JSON.parse()

Had to fix some code positioning to allow for this.
First step of big rewrite. Massive reduction in code duplication from
creating a generic LinePage file which can be dynamically set to use
either a Red Line or Green Line-specific Model.
Added overflow menu for Settings and About.

Added AboutPopover for About information.
Added Settings Page. All it contains for now is an experimental "Default Line" selector.

Added U1DB persistence for the default line.