Highlight lines when hovering legend; stick popover selection when clicked

Replaced legend FlexTable with new LegendTable class (for hover events)
RoutePopover ctor now requires the PhotoTopo object
Also hook into RP close handler for both click background and click X

Signed-off-by: Dean Rollins <deano.dinosaur@gmail.com>
Update dev page with latest Step Tier guide xml (with complete topo lines)

Signed-off-by: Dean Rollins <deano.dinosaur@gmail.com>
gitignore for GWT cache stuff

Signed-off-by: Dean Rollins <deano.dinosaur@gmail.com>