make rclick work from settings, step 1

split the reading of rclick trees and the generation of the
menus, just as the reading of @button scripts and binding
of callbacks is split for @buttons @buttons

Leo build: 20140818200303
step 2 working, call for @settings @buttons @buttons

Leo build: 20140818210415
tidy up code locations etc.

Leo build: 20140819105354
Merge rclick_settings, rclick working in @buttons in settings files

Leo build: 20140819110246