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/Tab.hpp

@@ -39,6 +39,8 @@
 namespace Slic3r {
 namespace GUI {
 
+class TabPresetComboBox;
+
 // Single Tab page containing a{ vsizer } of{ optgroups }
 // package Slic3r::GUI::Tab::Page;
 using ConfigOptionsGroupShp = std::shared_ptr<ConfigOptionsGroup>;
@@ -113,7 +115,7 @@ protected:
     Preset::Type        m_type;
 	std::string			m_name;
 	const wxString		m_title;
-	PresetBitmapComboBox*	m_presets_choice;
+	TabPresetComboBox*	m_presets_choice;
 	ScalableButton*		m_search_btn;
 	ScalableButton*		m_btn_save_preset;
 	ScalableButton*		m_btn_delete_preset;
@@ -206,8 +208,6 @@ protected:
 	bool				m_is_nonsys_values{ true };
 	bool				m_postpone_update_ui {false};
 
-	size_t				m_selected_preset_item{ 0 };
-
     void                set_type();
 
     int                 m_em_unit;
@@ -320,7 +320,6 @@ public:
 
 	DynamicPrintConfig*	get_config() { return m_config; }
 	PresetCollection*	get_presets() { return m_presets; }
-	size_t				get_selected_preset_item() { return m_selected_preset_item; }
 
 	void			on_value_change(const std::string& opt_key, const boost::any& value);