Added Node.clone_node utility.
Added Node.clone_node utility.

A method for cloning nodes. I expect this one to work on all descandants, but
it can be overriden if a node has special needs. It seems natural to put
such core functionality in the node classes rather than in a visitor.

dahebolangkuan/cython,hpfem/cython,achernet/cython,roxyboy/cython,c-blake/cython,acrispin/cython,JelleZijlstra/cython,acrispin/cython,encukou/cython,hickford/cython,larsmans/cython,slonik-az/cython,ABcDexter/cython,dahebolangkuan/cython,larsmans/cython,slonik-az/cython,mrGeen/cython,mrGeen/cython,slonik-az/cython,scoder/cython,hpfem/cython,andreasvc/cython,acrispin/cython,dahebolangkuan/cython,acrispin/cython,mcanthony/cython,fperez/cython,rguillebert/CythonCTypesBackend,ChristopherHogan/cython,cython/cython,dahebolangkuan/cython,fperez/cython,fabianrost84/cython,madjar/cython,encukou/cython,andreasvc/cython,ChristopherHogan/cython,bzzzz/cython,hickford/cython,bzzzz/cython,marscher/cython,da-woods/cython,mcanthony/cython,ABcDexter/cython,acrispin/cython,cython/cython,madjar/cython,encukou/cython,fperez/cython,larsmans/cython,da-woods/cython,hickford/cython,da-woods/cython,mcanthony/cython,cython/cython,rguillebert/CythonCTypesBackend,bzzzz/cython,madjar/cython,encukou/cython,scoder/cython,marscher/cython,marscher/cython,fabianrost84/cython,larsmans/cython,andreasvc/cython,madjar/cython,ChristopherHogan/cython,scoder/cython,hhsprings/cython,c-blake/cython,fperez/cython,achernet/cython,madjar/cython,slonik-az/cython,achernet/cython,hhsprings/cython,cython/cython,rguillebert/CythonCTypesBackend,marscher/cython,larsmans/cython,rguillebert/CythonCTypesBackend,c-blake/cython,roxyboy/cython,dahebolangkuan/cython,mcanthony/cython,achernet/cython,hickford/cython,roxyboy/cython,ABcDexter/cython,andreasvc/cython,achernet/cython,da-woods/cython,hhsprings/cython,fabianrost84/cython,mrGeen/cython,hpfem/cython,slonik-az/cython,scoder/cython,c-blake/cython,marscher/cython,hhsprings/cython,ABcDexter/cython,mrGeen/cython,JelleZijlstra/cython,roxyboy/cython,fabianrost84/cython,mrGeen/cython,fperez/cython,JelleZijlstra/cython,bzzzz/cython,hhsprings/cython,hpfem/cython,c-blake/cython,hpfem/cython,JelleZijlstra/cython,encukou/cython,fabianrost84/cython,roxyboy/cython,mcanthony/cython,hickford/cython,JelleZijlstra/cython,ABcDexter/cython,andreasvc/cython