Create pgr_contractionDeadEnd new contraction function

[cvvergara]

Ne function:

signature:

pgr_contractionDeadEnd([Edges SQL](file:///home/vicky/pgrouting/pgrouting/cvvergara/build/doc/html/en/pgr_contractionDeadEnd.html#edges-sql), [options])
options: [directed, forbidden_vertices]
Returns set of (type, id, contracted_vertices, source, target, cost)

Example execution:

SELECT * FROM pgr_contractionDeadEnd(
  'SELECT id, source, target, cost, reverse_cost FROM edges',
  directed => false);
 type | id | contracted_vertices | source | target | cost
------+----+---------------------+--------+--------+------
 v    |  4 | {2}                 |     -1 |     -1 |   -1
 v    |  6 | {5}                 |     -1 |     -1 |   -1
 v    |  7 | {1,3}               |     -1 |     -1 |   -1
 v    |  8 | {9}                 |     -1 |     -1 |   -1
 v    | 14 | {13}                |     -1 |     -1 |   -1
(5 rows)