Open inspector fullscreen and exploit monitor resolution, see #1474, #5591

- filecatalog.cc: add shortcuts
    'f' for image on full screen
    'Shift' 'f' for 100% crop on full screen
    (synchronization with mouse move as before with dual monitors)
- filepanel.cc: don't create inspector tab
- inspector.cc, inspector.h:
    create separate window for inspector
    scale image if requested
    exploit device scaling for full monitor resolution under macOS

rtgui/filecatalog.cc

@@ -42,6 +42,7 @@
 #include "pathutils.h"
 #include "thumbnail.h"
 #include "toolbar.h"
+#include "inspector.h"
 
 using namespace std;
 
@@ -2503,6 +2504,15 @@ bool FileCatalog::handleShortcutKey (GdkEventKey* event)
         }
     }
 
+    if (!ctrl && !alt) {
+        switch (event->keyval) {
+        case GDK_KEY_f:
+        case GDK_KEY_F:
+            fileBrowser->getInspector()->showWindow(!shift);
+            return true;
+        }
+    }
+
     return fileBrowser->keyPressed(event);
 }