new class PointGenerator; add some attributes and member functions

Add a PointGenerator class to generate different data points in
different points
Add a VECTOR class in GeoDefinition.h
Add an attribute "id" in the VERTEX class, also add some member
functions.

In DCEL.h,
Add "iterator" attribute in VertexObject, FaceObject and HalfedgeObject
for the deletion operation in the future.

Add "add", "remove", operator << functions in DCEL.h

Add an attribute "Vertex v" in VertexObject class