[wktraster] Updates to the readme.txt accompanying WKT Raster experimental build

[pracine]

Some updates for the readme accompanying the WKT Raster experimental build package

1) Line 3 noting that you may need to replace geometry_gist_joinsel is obsolete since this ticket as been fixed.

2) In the "loading raster data" part, we should mention that it is also necessary to download the GDAL binaries (gdalwin32exe160.zip) from ​http://download.osgeo.org/gdal/win32/1.6/ before installing the Python GDAL bindings.

3) It is also necessary to install numpy from ​http://sourceforge.net/projects/numpy/files/ before installing the Python GDAL bindings.

By the way it is a bit complicated to get from the PostGIS main web page to the Experimental build page... Maybe all Windows build could be in the same page. I know the PostGIS site is very limitating in terms of page structure. Maybe a table in the wiki would be a better place to make a complex page with all the option in the same page...

[robe]

Strange I thought I had mentioned that and the numpy dependency -- unless I accidentally included an older readme in my last set. Anyrate I think Tamas's might be a better option

​http://vbkto.dyndns.org/sdk/

Since his package includes GDAL 1.7 (and trunk if people want) and the python bindings.

[pracine]

4) Don't forget also to put line 4 (Copy the contents of bin to your PostgreSQL bin folder (gdal2wktraster.py, libgdal.dll) to bin folder of your PostgreSQL install.) before 3