Add error reporting for scripts run from the Scripts menu.
Make iTermSelection -clearSelection do nothing if there is no selection. It was calling selectionDidChange:, which forced a redraw. That was a problem because when not saving lines to scrollback in the alternate screen we would clear the selection on every linefeed and that killed performance. Issue 794 comments 22-27.
Merge branch 'master' of https://github.com/gnachman/iTerm2