Edges edge object and related functions. Edges are derived from #GtsSegment. They are used to define #GtsTriangle. @klass: @obj: @obj: The edge class. No virtual function associated. @parent_class: The edge object. @segment: The parent object. @triangles: List of #GtsTriangle using this edge. @Returns: @klass: @v1: @v2: @Returns: @e: @with: @s: @e: @Returns: @e: @surface: @Returns: @e: @Returns: @e: @surface: @Returns: @e: @Returns: @e: @Returns: @e: @s: @Returns: @e: @s: @f1: @f2: @Returns: @v: @e: @s: @data: @Returns: @e: @s: @encroaches: @data: @Returns: @edges: @Returns: @vertices: @parent: @Returns: @e: @s: