New layout preferences to maximize editor control space

see issue 759

rtgui/options.h

@@ -144,6 +144,8 @@ class Options {
     Glib::ustring sndLngEditProcDone;
     double sndLngEditProcDoneSecs;  // Minimum processing time seconds till the sound is played
     bool tunnelMetaData;  // Pass through IPTC and XMP unchanged
+    int histogramPosition;  // 0=disabled, 1=left pane, 2=right pane
+    bool showProfileSelector;
 
     Options ();