Add WKBReader::read() & WKBWriter::write() PHP bindings

Includes tests.
Patch by Benjamin Morel <benjamin.morel@gmail.com>

Signed-off-by: Sandro Santilli <strk@keybit.net>

git-svn-id: http://svn.osgeo.org/geos/trunk@4015 5242fede-7e19-0410-aef8-94bd7d2200fb
OverlayOp: restrict intersection computations by the target extent
Restrict self-noding to target env too

Also, disable the optimization for DIFFERENCE, which seem to fail
in some cases
Restrict copyPoints to target envelope

Re-enable optimization for DIFFERENCE,
disable for non-floating precision models (Envelope->covers does
not take precision model in consideration)