Merge some BS1.7 changes:

internal_solid_infill_pattern

src/libslic3r/Fill/FillBase.hpp

@@ -78,6 +78,7 @@ struct FillParams
     float           no_extrusion_overlap{ 0.0 };
     const           PrintRegionConfig* config{ nullptr };
     bool            dont_sort{ false }; // do not sort the lines, just simply connect them
+    bool            can_reverse{true};
 };
 static_assert(IsTriviallyCopyable<FillParams>::value, "FillParams class is not POD (and it should be - see constructor).");