Implementation for #6216

* Implementation for #6216 - Make number keys select extruder when object treeview has focus
+ deleted unused extruder_selection()
+ Fixed notification after splitting of the solid object

* Follow up 85a10268b9 - OSX implementation
+ Added shortcuts description to the "Keyboard Shortcuts" dialog

* Workaround to use "+/-" and numbers shortcuts on Linux
+ Fixed build on Linux

* OSX specific: fixed a work of keyboard accelerators from numbers on NumPad keyboard

* KBShortcutsDialog: fixed shortcuts for "Preferences" and "Show/Hide 3Dconnexion devices settings dialog, if enabled" under osx
and "Set Printable/Unprintable" and "Set extruder" under Linux
 + OSX specific: Added minimize of the application on "Cmd+M"

* Hot-fix for 6efeb9d6b4

* Removed Linux specific workaround

src/slic3r/GUI/Search.cpp

@@ -7,6 +7,7 @@
 #include <boost/nowide/convert.hpp>
 
 #include "wx/dataview.h"
+#include "wx/numformatter.h"
 
 #include "libslic3r/PrintConfig.hpp"
 #include "libslic3r/PresetBundle.hpp"
@@ -45,6 +46,11 @@ static char marker_by_type(Preset::Type type, PrinterTechnology pt)
 	}
 }
 
+std::string Option::opt_key() const
+{
+    return boost::nowide::narrow(key).substr(2);
+}
+
 void FoundOption::get_marked_label_and_tooltip(const char** label_, const char** tooltip_) const
 {
     *label_   = marked_label.c_str();