fix: schemas/util.sql: materialize_query(): 1st param should be named table_, not view_

schemas/util.sql: added drop_view()

schemas/util.sql: added materialize_query()

/README.TXT: Schema changes: clarified that the staging tables should only be reinstalled if needed

/README.TXT: put ... around all uppercased text, for consistency

_license/non-open-source/applies_to.txt: clarified that this is an exclusions list, not an inclusions list, in terms of what's open-source

validation/aggregating/*/*.sql, schemas/vegbien.sql, lib/runscripts/validations.pg.sql.run, inputs/bien2_traits/validations.sql: added _ to beginning of each view name so the validation views would sort at the top in the datasource's tables list. this will also make the validation result sets easily distinguishable from the data tables.

validation/aggregating/*/*.sql: renamed views to match the current naming scheme in the DB. these files still need to be kept up-to-date because there are some queries that haven't been implemented yet, and therefore exist only in these files, not the DB.

schemas/util.sql: ifnull(): use COALESCE instead, because it turns out that MySQL's IFNULL is just a special case of this

added inputs/bien2_traits/validations.sql, from validation/aggregating/traits/BIEN2_traits/bien3_validations_traits_original_mysql.VegCore.sql