Pointer cleanup (#242)

- Made greater use of smart pointers, eliminating many instances of manual memory management
- Do not use pointers at all for many non-polymorphic classes
- Assorted other code cleanup

model/FramePath.h

@@ -36,14 +36,14 @@ namespace glabels
 
 		public:
 			FramePath( const QPainterPath& path,
-			           const Distance&     xWaste,
-			           const Distance&     yWaste,
-			           const Units&        originalUnits,
+			           Distance            xWaste,
+			           Distance            yWaste,
+			           Units               originalUnits,
 			           const QString&      id = "0" );
 
 			FramePath( const FramePath& other ) = default;
 
-			Frame* dup() const override;
+			std::unique_ptr<Frame> clone() const override;
 
 			Distance xWaste() const;
 			Distance yWaste() const;
@@ -53,14 +53,16 @@ namespace glabels
 			Distance w() const override;
 			Distance h() const override;
 
-			QString sizeDescription( const Units& units ) const override;
+			QString sizeDescription( Units units ) const override;
 
-			bool isSimilarTo( Frame* other ) const override;
+			bool isSimilarTo( const Frame& other ) const override;
 
 			const QPainterPath& path() const override;
 			const QPainterPath& clipPath() const override;
-			QPainterPath marginPath( const Distance& xSize,
-			                         const Distance& ySize ) const override;
+			QPainterPath marginPath( Distance xSize, Distance ySize ) const override;
+
+                        // Debugging support
+			void print( QDebug& dbg ) const override;
 
 
 		private:
@@ -79,8 +81,4 @@ namespace glabels
 }
 
 
-// Debugging support
-QDebug operator<<( QDebug dbg, const glabels::model::FramePath& frame );
-
-
 #endif // model_FramePath_h