Port the Edge splitting robustness improvement to ST_Split

[strk]

I think ModEdgeSplit? and NewEdgeSplit? may be using ST_Split directly, it shall be checked if the robustness improvement added in the former should be ported to the latter, and then have the former use the latter.

Less code to maintain is always good.

See r9539 to understand what I'm talking about

[strk]

ST_Split seems unaffected:

strk=# with inp as ( select '01020000000400000000000000000034400000000000002440000000000000244000000000000024400000000000002240000000000000284000000000000024400000000000003440'::geometry as line, '010100000000000000000022400000000000002840'::geometry as point ), spl as ( select ST_Split(line, point) as split, point  from inp ), spall as ( select st_geometryn(split, 1) as sp1, st_geometryn(split, 2) as sp2, point from spl ) select st_equals(ST_EndPoint(sp1), point), st_equals(ST_StartPoint(sp2), point) from spall;
 st_equals | st_equals 
-----------+-----------
 t         | t
(1 row)

So maybe let's keep this ticket to use ST_Split from ST_ModEdgeSplit and ST_NewEdgesSplit

[strk]

Done with r9624