GEOS Support

[Steve Lime]

Hi all: I did commit the port of the C++ support for GEOS to the new C-API. Seems to work well in testing. I wrapped all the meaningful GEOS methods:

  - buffer, intersection, union, difference, symDifference, boundary, getCentroid, convexHull

  - contains, within, overlaps, intersects, disjoint, equals, touches, crosses

  - area, length, distance

and have included those in the SWIG binding for shapeObj's.

To do's or gotchas:

  - configure needs to detect a minimum version of GEOS (2.2.2 or higher - that's when length and area were exposed to C API)

  - need to handle z coordinates if enabled in MapServer

  - error handling ain't great, it's not as easy to get at GEOS errors as before. We could define a GEOS error handler and register it when initializing
    the library but I worry about conflicts with PostGIS or OGR that also use it.

  - there's one MapScript issue. There already is a contains method that takes a pointObj. I created an overloaded method for contains that takes
    a shapeObj. In perl that's ok, but I'm not sure about other languages.

  - PHP/MapScript needs to be updated.

I'll update all necessary bugs in Bugzilla with details. Let me know if you run into issues beside the one already fixed...

Steve