rtc: single loop to merge MRU
rtc _forEachPaneOrPanes, fail Fast, tests, throw exception in setActivePane(invalid)
fix previous commit
rtc
throw syntax
addView(s) => addToWorkingSet
move views->workingSet
more paneView->workingSet stuff, events and remove->close conversion
simplify pane.removeView/pane.removeViews
paneViewSort/PaneViewListView=>..WorkingSet.., tests, test files and directories as well
merge with splitview-1x2