Create a legacy_compatibility_layer.sql.in.c

[robe]

There are several functions commonly used by GUIs and web apps or even our old code. Moving to PostGIS 2.0 will make it difficult for people to use these apps or even restore some of their tables unless they install the legacy.sql.

Legacy.sql has a bit too much. So my plan to conquer all worlds and minimize on redundancy is the following

1) remove these functions from legacy.sql.in.c: srid, ndims, AsText, AsBinary, extent are first that come to mind since not having some of these prevent tables helped by populate_geometry_columns from being restored.

2) The above listed will get moved to a new file called legacy_compatibility_layer.sql.in.c

3) Include this new file in legacy.sql.in.c

So this will allow people to have a fairly clean slate but still be for the most part cross functional with old code.

4) add legacy_compatibility_layer.sql as a target build

4) Update the hard_upgrade instructions to be:

build new database run legacy_compatibility_layer.sql restore old database run upgrade minor script run uninstall_legacy.sql (if they want to get rid of old junk, but let them know they can safely ignore errors since the uninstall will won't be able to uninstall things in use in views, sql functions, or table constraints)