Create standard PostGIS example datasets

[dbaston]

Adding this after some discussion #postgis the other day...

It would be great to have a couple of standard datasets distributed with PostGIS, either as part of the core extension or a separate "postgis_examples" extension. Much like the standard data sets available in R, the standard PostGIS datasets could be used throughout the documentation instead of each function needing to derive its own examples using WKT.

[darkblueb]

for your consideration are:

​GRASS NC

​natural_earth2

these and others are used on the ​OSGeo-Live disk for some time..

[robe]

Milestone renamed