Changed location of vendor specific thumbnail images of printers:

These images are newly stored inside the resources/profiles/VENDOR_NAME/,
they should be named by the printer_model identifier suffixed with
"_thumbnail.png"

All the existing printer thumbnails were moved and renamed,
thumbnails for the 3rd party printers were added, marked as Beta.

src/slic3r/GUI/ConfigWizard.cpp

@@ -188,7 +188,7 @@ PrinterPicker::PrinterPicker(wxWindow *parent, const VendorProfile &vendor, wxSt
 
         wxBitmap bitmap;
         int bitmap_width = 0;
-        const wxString bitmap_file = GUI::from_u8(Slic3r::var((boost::format("printers/%1%_%2%.png") % vendor.id % model.id).str()));
+        const wxString bitmap_file = GUI::from_u8(Slic3r::resources_dir() + "/profiles/" + vendor.id + "/" + model.id + "_thumbnail.png");
         if (wxFileExists(bitmap_file)) {
             bitmap.LoadFile(bitmap_file, wxBITMAP_TYPE_PNG);
             bitmap_width = bitmap.GetWidth();