updated 2D examples

git-svn-id: http://svn.code.sf.net/p/netgen-mesher/code/netgen@812 38e36fca-e102-11dd-b6c5-65a6809f2f0c
new functions added

git-svn-id: http://svn.code.sf.net/p/netgen-mesher/code/netgen@813 38e36fca-e102-11dd-b6c5-65a6809f2f0c
new method "Append" to add segments

git-svn-id: http://svn.code.sf.net/p/netgen-mesher/code/netgen@814 38e36fca-e102-11dd-b6c5-65a6809f2f0c