Fix of G-code Viewer not loading .gco files #5536

".gcode", ".gco", ".g" and ".ngc" were considered to be G-code file
extensions by the G-code import / export file dialogs, but not by
various other functions. Now the G-code extension is tested by
a single function is_gcode_file(string).

src/libslic3r/Config.cpp

@@ -589,7 +589,7 @@ void ConfigBase::setenv_() const
 
 void ConfigBase::load(const std::string &file)
 {
-    if (boost::iends_with(file, ".gcode") || boost::iends_with(file, ".g"))
+    if (is_gcode_file(file))
         this->load_from_gcode_file(file);
     else
         this->load_from_ini(file);