osm2pgsql style: merge main tag and pre-filter handling

Defining a tag as deleteable/extratag and main tag is mutually exclusive
and deleting certain key/value combinations to exclude them from being
used as a main tag is confusing. By merging the handling, such
excludes can now be made explicit in the main list.

By using the same lookup table, it is now also possible to have a
short-cut for uninteresting objects.