ST_GeoHash should support geography type without cast

[toofishes]

Given that it operates on latitude/longitude coords, and most of the other export/output functions take both geometry and geography, I was surprised to see this one didn't.

database=> select ST_GeoHash('POINT(0 0)');
      st_geohash      
----------------------
 7zzzzzzzzzzzzzzzzzzz
(1 row)

database=> select ST_GeoHash('POINT(0 0)'::geography);
ERROR:  function st_geohash(geography) does not exist
LINE 1: select ST_GeoHash('POINT(0 0)'::geography);
               ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

[pramsey]

Fair 'nuff! r10278

[strk]

testcase missing!

[pramsey]

ok fine, r10280

[robe]

and of course I think the below will no longer work

SELECT ST_GeoHash('POINT(0 0)');

Though I haven't confirmed. That'll teach'em -- they'll have to do

SELECT ST_GeoHash('POINT(0 0)'::geometry);

If my suspicion is correct, should we catalog this as a breaking change, or add the 'Unknown' hack.

We have same issue with ST_Segmentize BTW.

Anyrate we should probably add the unknown hack to the legacy file if we don't make it part of the core file.