Merge the Genome Browser channel's info (legend) icon functionality into the cog icon

[leehart]

Have the cog icon toggle both the channel config/settings AND the legend/info, and do away with the "i" icon.
This would simplify the interface. (At the loss of having one open but not the other.)
It would conflate the meanings of the two icons, "settings" and "info", (there was also an issue that users don't intuitively know that the info icon would open the legend) but maybe there is a better icon to suit the general purpose of showing/hiding stuff.