Introduction of Monotonous infill type. Fill no-sort only for monotonous

and ironing infills.

src/libslic3r/PrintConfig.cpp

@@ -418,18 +418,20 @@ void PrintConfigDef::init_fff_params()
     def->cli = "top-fill-pattern|external-fill-pattern|solid-fill-pattern";
     def->enum_keys_map = &ConfigOptionEnum<InfillPattern>::get_enum_values();
     def->enum_values.push_back("rectilinear");
+    def->enum_values.push_back("monotonous");
     def->enum_values.push_back("concentric");
     def->enum_values.push_back("hilbertcurve");
     def->enum_values.push_back("archimedeanchords");
     def->enum_values.push_back("octagramspiral");
     def->enum_labels.push_back(L("Rectilinear"));
+    def->enum_labels.push_back(L("Monotonous"));
     def->enum_labels.push_back(L("Concentric"));
     def->enum_labels.push_back(L("Hilbert Curve"));
     def->enum_labels.push_back(L("Archimedean Chords"));
     def->enum_labels.push_back(L("Octagram Spiral"));
     // solid_fill_pattern is an obsolete equivalent to top_fill_pattern/bottom_fill_pattern.
     def->aliases = { "solid_fill_pattern", "external_fill_pattern" };
-    def->set_default_value(new ConfigOptionEnum<InfillPattern>(ipRectilinear));
+    def->set_default_value(new ConfigOptionEnum<InfillPattern>(ipMonotonous));
 
     def = this->add("bottom_fill_pattern", coEnum);
     def->label = L("Bottom fill pattern");