Increare accuracy of area calculation

[hopfgartner]

In the case of polygons which are "far" away from the origin, as happens frequently in projected SRS, the applied change may increase the accuracy of the area calculation by some order of magnitude. Doing some tests on UTM32N geometries and comparing the result with the result calculated with a routine written with ​http://de.php.net/manual/en/book.bc.php the accuracy improved by 4 to 5 orders of magnitude. The patch is against PostGIS 1.5.2.

[strk]

Sounds good to me. Would you feel like attaching an updated patch against trunk and make sure the regression test still passes all ? Even better if you could _add_ a test in the existing tickets.sql file.

[hopfgartner]

This implements the same formula as the patches submitted to JTS, ​http://sourceforge.net/mailarchive/forum.php?thread_name=4E8F2EE8.6010505%40telus.net&forum_name=jts-topo-suite-user, and GEOS, ​http://trac.osgeo.org/geos/ticket/485.

[pramsey]

Applied to trunk at r8068

[pramsey]

Applied to 1.5 at r8071 and 1.4 at r8072