[raster] Support reprojection on import

[strk]

shp2pgsql recently got a switch to reproject vectors during import (-s <from>:<to>). It would be nice to have the same switch in raster2pgsql, especially for handling overviews that are more annoying to deal with after import.

[strk]

r12789 in trunk

[strk]

I'm reopening this because in-db reprojection is very limited. The main 2 limits are:

1. Tiled output can result in different tiles using different scales (easy, if you come from 4326 and project to webmercator/3857)
2. You cannot use COPY mode (-Y)

Ideally the transformation would be done via GDAL instead.

[strk]

One problem with having reprojection done by GDAL is that we cannot use a "srid" but rather we need an "srs". Constructing it from a query into spatial_ref_sys would break current isolation between the loader and the database.

[robe]

Milestone renamed