Code refactoring:

- PresetCombpBoxes are extracted to the separate file.
- All preset icons are moved to the PresetComboBox from Preset and PresetBundle
- First "steps" to add physical printers to the printers list on the sidebar.

src/slic3r/GUI/wxExtensions.hpp

@@ -95,37 +95,6 @@ public:
     void OnListBoxSelection(wxCommandEvent& evt);
 };
 
-namespace Slic3r {
-namespace GUI {
-// ***  PresetBitmapComboBox  ***
-
-// BitmapComboBox used to presets list on Sidebar and Tabs
-class PresetBitmapComboBox: public wxBitmapComboBox
-{
-public:
-    PresetBitmapComboBox(wxWindow* parent, const wxSize& size = wxDefaultSize);
-    ~PresetBitmapComboBox() {}
-
-#ifdef __APPLE__
-protected:
-    /* For PresetBitmapComboBox we use bitmaps that are created from images that are already scaled appropriately for Retina
-     * (Contrary to the intuition, the `scale` argument for Bitmap's constructor doesn't mean
-     * "please scale this to such and such" but rather
-     * "the wxImage is already sized for backing scale such and such". )
-     * Unfortunately, the constructor changes the size of wxBitmap too.
-     * Thus We need to use unscaled size value for bitmaps that we use
-     * to avoid scaled size of control items.
-     * For this purpose control drawing methods and
-     * control size calculation methods (virtual) are overridden.
-     **/
-    virtual bool OnAddBitmap(const wxBitmap& bitmap) override;
-    virtual void OnDrawItem(wxDC& dc, const wxRect& rect, int item, int flags) const override;
-#endif
-};
-
-}
-}
-
 
 // ***  wxDataViewTreeCtrlComboBox  ***