Improved stringbuffer again. Always write directly into the buffer, no more memcpy...

Improved stringbuffer again. Always write directly into the buffer, no more memcpy'ing. Change return values for printing calls to int, so that print errors can be detected and handled by the layers above, if desired.

git-svn-id: http://svn.osgeo.org/postgis/trunk@5461 b70326c6-7e19-0410-871a-916f4a2858ee