New function pgr_findCloseEdges

[cvvergara]

Fixes #2317

Changes proposed in this pull request:
SQL only function with 2 signatures one for one point and another for many points

pgr_findCloseEdges(Edges SQL, point, tolerance  [cap, partial, dryrun])
pgr_findCloseEdges(Edges SQL, points, tolerance  [cap, partial, dryrun])
RETURNS SET OF (edge_id, fraction side, distance, geom, edge)
OR EMPTY SET

The functions are ready to use with any withPoints function:

SELECT * FROM pgr_withPoints(
  $e$ SELECT * FROM edges $e$,
  $p$ SELECT edge_id, round(fraction::numeric, 2) AS fraction, side
      FROM pgr_findCloseEdges(
        $$SELECT id, geom FROM edges$$,
        (SELECT geom FROM pointsOfInterest WHERE pid = 5),
        0.5, cap => 2)
  $p$,
  1, ARRAY[-1, -2]);
 seq | path_seq | end_pid | node | edge | cost | agg_cost
-----+----------+---------+------+------+------+----------
   1 |        1 |      -2 |    1 |    6 |    1 |        0
   2 |        2 |      -2 |    3 |    7 |    1 |        1
   3 |        3 |      -2 |    7 |    8 |  0.9 |        2
   4 |        4 |      -2 |   -2 |   -1 |    0 |      2.9
   5 |        1 |      -1 |    1 |    6 |    1 |        0
   6 |        2 |      -1 |    3 |    7 |    1 |        1
   7 |        3 |      -1 |    7 |    8 |    1 |        2
   8 |        4 |      -1 |   11 |    9 |    1 |        3
   9 |        5 |      -1 |   16 |   16 |    1 |        4
  10 |        6 |      -1 |   15 |    3 |    1 |        5
  11 |        7 |      -1 |   10 |    5 |  0.8 |        6
  12 |        8 |      -1 |   -1 |   -1 |    0 |      6.8
(12 rows)

Also the function can be used as described in #2317 for the creation of a points of interest table.

For the new function

• sql code
• pgtap tests
• docqueries examples
• documentation

For the withPoints function

• at least one example usage on each function documentation page
• Using on sample data the function to create the pointsOfInterest table

@pgRouting/admins