Added chart feature based on RGraph libraries.

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Switched display feedback scores default from 1 ("yes") to 0 ("no") upon upgrade.

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>
Fixed 2 small Chart bugs, including one in the RGraph.radar.js library.

Signed-off-by: Joseph Rézeau <moodle@rezeau.org>