Support full POSIX-style time zone: EST+3, PST-3, etc.

We probably support a superset of the spec, but I don't have the spec
 to confirm this.
Update regression tests to include tests for this format.
Update geometry.out with results from Linux RH 5.2 system
(for last decimal place).

src/test/regress/expected/geometry.out

@@ -150,11 +150,11 @@ SELECT '' as six, box(f1) AS box FROM CIRCLE_TBL;
  six |                                    box                                     
 -----+----------------------------------------------------------------------------
      | (2.12132034355964,2.12132034355964),(-2.12132034355964,-2.12132034355964)
-     | (71.7106781186548,72.7106781186548),(-69.7106781186548,-68.7106781186548)
-     | (4.53553390593274,6.53553390593274),(-2.53553390593274,-0.535533905932738)
+     | (71.7106781186547,72.7106781186547),(-69.7106781186547,-68.7106781186547)
+     | (4.53553390593274,6.53553390593274),(-2.53553390593274,-0.535533905932737)
      | (3.12132034355964,4.12132034355964),(-1.12132034355964,-0.121320343559642)
      | (107.071067811865,207.071067811865),(92.9289321881345,192.928932188135)
-     | (170.710678118655,70.7106781186548),(29.2893218813452,-70.7106781186548)
+     | (170.710678118655,70.7106781186547),(29.2893218813453,-70.7106781186547)
 (6 rows)
 
 -- translation
@@ -503,11 +503,11 @@ SELECT '' AS twentyfour, c1.f1 AS circle, p1.f1 AS point, (p1.f1 <-> c1.f1) AS d
    WHERE (p1.f1 <-> c1.f1) > 0
    ORDER BY distance, circle, point using <<;
  twentyfour |     circle     |   point    |     distance     
-------------+----------------+------------+-------------------
-            | <(100,0),100>  | (5.1,34.5) | 0.976531926977965
+------------+----------------+------------+------------------
+            | <(100,0),100>  | (5.1,34.5) | 0.97653192697797
             | <(1,2),3>      | (-3,4)     | 1.47213595499958
             | <(0,0),3>      | (-3,4)     |                2
-            | <(100,0),100>  | (-3,4)     |  3.07764064044151
+            | <(100,0),100>  | (-3,4)     | 3.07764064044152
             | <(100,0),100>  | (-5,-12)   | 5.68348972285122
             | <(1,3),5>      | (-10,0)    | 6.40175425099138
             | <(1,3),5>      | (10,10)    | 6.40175425099138