OGR SRS support for +datum=nzgd49 without EPSG authority code

[hamish]

Hi,

re. a tangent of QGIS's bug # 1875 et al.,

​https://trac.osgeo.org/qgis/ticket/1875#comment:43

the attached patch adds the WKT text string for the NZGD49 datum into OGR's SRS conversion logic.

the matched text is the same as shown by proj -ld and in the WKT of this online EPSG portal:

​http://spatialreference.org/ref/epsg/27200/

I'm not sure if it is desired to open the floodgates to all the datums of the world having this sort of #defined support, but as proj -ld only lists 10 possibilities it doesn't seem too outrageous to ask. A more general patch would be to ensure that all ten of the __datum_id's__ reported by proj -ld have #defines containing their space-to-underscore(?) text line equivalents. But I'm not familiar enough with the others to comment about if that's a wise idea or not.

(fwiw the datums GRASS knows beyond OGR/PROJ can be found at

​https://trac.osgeo.org/qgis/ticket/1875#comment:33 )

thanks, Hamish

[hamish]

patch to add nzgd49 support using WKT name alone

[Even Rouault]

In trunk (r17546) : Improve recognition of WKT text strings when translating into proj4 hard-coded datum names, in particular nzgd49 (also add ggrs87, carthage, hermannskogel, ire65); Fix ellipsoid parameters for modified airy

[hamish]

cheers- the result is once again above and beyond the request.