Fix for bug #310 : Unify prototypes of WKTReader and WKBReader constructor

Fixes bug #310: Unify prototypes of WKTReader and WKBReader constructor.
Changed the WKTReader constructor's argument to const GeometryFactory& instead
of const GeometryFactory*.

All the tests have been updated (the largest part of the patch), and geos_unit.exe's tests pass and TestSweepLineSpeed runs cleanly.