CURA-12096 move gradual flow plugin back into the engine core

include/LayerPlan.h

@@ -779,6 +779,12 @@ class LayerPlan : public NoCopy
      */
     void applyBackPressureCompensation();
 
+    /*!
+     * If enabled, applies the gradual flow acceleration splitting, that improves printing quality when printing at very high speed,
+     * especially with a bowden extruder.
+     */
+    void applyGradualFlow();
+
 private:
     /*!
      * \brief Compute the preferred or minimum combing boundary

include/geometry/LinesSet.h

@@ -158,7 +158,7 @@ class LinesSet
     template<class OtherLineType>
     void push_back(LinesSet<OtherLineType>&& lines_set);
 
-    /*! \brief Pushes an entier set at the end */
+    /*! \brief Pushes an entire set at the end */
     void push_back(const LinesSet& other)
     {
         lines_.insert(lines_.end(), other.lines_.begin(), other.lines_.end());

include/geometry/PointsSet.h

@@ -78,6 +78,12 @@ class PointsSet
         points_.push_back(point);
     }
 
+    /*! \brief Pushes an entire set at the end */
+    void push_back(const PointsSet& other)
+    {
+        points_.insert(points_.end(), other.points_.begin(), other.points_.end());
+    }
+
     void emplace_back(auto&&... args)
     {
         points_.emplace_back(std::forward<decltype(args)>(args)...);