Added possibility for upload to Duet

Further changes:
- Added new configuration option Host Type
- Added abstract base class for future printer hosts
- Moved location of upload dialog (also made it a little bit more configureable)
- added possibility to send file via postfield instead a new frame

xs/src/slic3r/GUI/Tab.hpp

@@ -321,7 +321,8 @@ class TabPrinter : public Tab
 	bool		m_rebuild_kinematics_page = false;
 public:
 	wxButton*	m_serial_test_btn;
-	wxButton*	m_octoprint_host_test_btn;
+	wxButton*	m_print_host_test_btn;
+	wxButton*	m_printhost_browse_btn;
 
 	size_t		m_extruders_count;
 	size_t		m_extruders_count_old = 0;