- Add distinct binary predicates test suppor in XMLTester

- IsValidTest.cpp in source/test ?

- Check how to disable GEOS_VERSION define on command line
  (or make GEOS_VERSION define in version.h optional)
  not a major problems, just makes the compiler issue some warninigs.

- Check GeometryEditor behaviour (modify passed geom or create a new one ?)
  [not documented]

- Remove all explicit heap allocations for private static members.
