schemas/vegbien.sql: datasource_rm(): documented how to calculate runtime

schemas/vegbien.sql: datasource_rm(): documented runtime for ACAD: 30 s; 0.61 ms/row

inputs/input.Makefile: rm: use new datasource_rm(), which encapsulates the schema-specific aspects of removing a datasource

bugfix: schemas/vegbien.sql: datasource_rm(): set_config(): don't name the is_local param because it is not a named parameter

schemas/vegbien.sql: added datasource_rm(). this uses an internal schema-scoping parameter to ensure that the function always operates on tables in the schema it was defined in, rather than tables in the search_path. this ensures that when the public schema is renamed (e.g. from an imported version), the function will continue to operate on its own schema rather than whichever schema happens to be called public. this avoids any surprises if you are trying to remove a datasource in one schema, and don't want it to unintentionally be removed in another schema instead.

schemas/util.sql: added schema_ident()

schemas/util.sql: added schema(regtype), schema(anyelement)

inputs/.TNRS/schema.sql: added covering indexes on foreign keys where needed. this enables rows to be cascadingly deleted without a full table scan.

schemas/vegbien.sql: added covering indexes on foreign keys where needed. this enables rows to be cascadingly deleted without a full table scan.

planning/timeline/timeline.2013.xls: increased font size for better readability at 100% (which is also the printed size). note that the timeline is normally zoomed in, so you don't see the actual font size.