Need a way for wkt generator to auto compute arrows

[robe]

Cases like this - I actually had to remember stuff I learned in grade school to draw arrows in this:

 http://www.postgis.org/documentation/manual-svn/ST_LineCrossingDirection.html

Life shouldn't be so hard.

Strk is also complaining about how offset has no arrows to accentuate the directionality of the function.

 http://www.postgis.org/documentation/manual-svn/ST_OffsetCurve.html