WIP: Refactored bridging flow from normal flow, new config value

'thick_bridges' to switch between the Slic3r vs. S3D/Cura/Ideamaker
way of printing 1st object layer over supports.
Simplified the PresetHints.

src/libslic3r/PrintConfig.cpp

@@ -2415,6 +2415,13 @@ void PrintConfigDef::init_fff_params()
     def->max = max_temp;
     def->set_default_value(new ConfigOptionInts { 200 });
 
+    def = this->add("thick_bridges", coBool);
+    def->label = L("Thick bridges");
+    def->category = L("Layers and Perimeters");
+    def->tooltip = L("Print bridges with round extrusions.");
+    def->mode = comAdvanced;
+    def->set_default_value(new ConfigOptionBool(true));
+
     def = this->add("thin_walls", coBool);
     def->label = L("Detect thin walls");
     def->category = L("Layers and Perimeters");