improve multiple results support

The specification talks exactly about -1:
> Returns: the current result as an update count;
> -1 if the current result is a ResultSet object or there are no more results

Other negative numbers can theoretically mean something different than „no more results“
e.g. unknown number of updates (?).

sqldk-relpipe convergence: integer type (relpipe already support signed integers)

fix license version: GNU GPLv3

change XMLNS for the configuration
Use The 'tag' URI Scheme <http://www.faqs.org/rfcs/rfc4151.html>
Upgrade local configuration:
sed 's@https://sql-dk.globalcode.info/xmlns/configuration@tag:globalcode.info,2018:sqldk/configuration@g' -i ~/.sql-dk/config.xml

transform the record formatter into the recfile formatter
still a human-readable format and very similar
but also machine-readable – can be processed in GNU Recutils and Relational pipes

getTableName() is needed for the metadata

support custom relation names in the XML formatter (added --relation CLI option)

sqldk-relpipe convergence started

back to the snapshot

Added tag v0.10 for changeset 0503996934e0

release: 0.10

switch to JUnit5

mavenized: sql-dk-parent

mavenized: jdbc-dk-driver

mavenized: sql-dk

mavenized: jdbc-loopback-driver