bugfix: inputs/*/Source/: use installed staging table (with blank-line data.csv) in order to also work with new-style import. this also fixes a benign diff between the by-row and by-col test outputs, where row-based import would not import the Source/ entries because there was not at least one row in the input. note that in order to ensure that all datasources are properly run, you need to check `svn st|sort` against the datasource schema names to see if any are missing.

inputs/*/logs: updated svn:ignore

inputs/*/*/logs: updated svn:ignore

bugfix: inputs/input.Makefile: SVN: add: don't add subdirs for datasources marked _no_import (e.g. datasources which only have an inputs/ dir to be listed in VegPath)

bugfix: inputs/*/Source/data.csv for new-style datasources: need to include a blank row (plus a blank header) so that the metadata values are imported at least once instead of zero times, now that there is an installed staging table that will be iterated over. the blank row did not used to be necessary, because db_xml.put_table() has a special case for metadata-only tables with no installed table, which avoids iterating over the table's rows.

lib/sql_io.py: put_table() (column-based import): complexity note: clarified that INSERT RETURNING throws an error on duplicate instead of returning the existing row. added blank line after ¶ for readability.

lib/sql_io.py: put_table() (column-based import): warning about triggers populating unique constraint-covered columns: corrected limitation to include only the unique constraint used to do the DISTINCT ON, since other unique constraints are not affected by column-based import. note that the primary key will normally not be the DISTINCT ON constraint, so trigger-populated natural keys are supported unless the input table contains duplicate rows for some generated keys.

inputs/*/Source/ for new-style datasources: use an actual staging table instead of a metadata-only table, so that metadata values can be stored in the staging table instead of the map.csv (as will be required by new-style import)

inputs/input.Makefile: SVN: $(svnFilesGlob): added data.csv, used to store versioned data (such as the empty data.csv used by Source/ tables which have their metadata in the map table instead)

schemas/util.sql: type_qual(), type_qual_name(): added comments to distinguish these similarly-named functions, one of which gets a type qualifier and the other of which gets a qualified name (not the name of a type qualifier, which one might otherwise assume)