-remattr
template: pers?clnt=<name|pass>&com=remattr&attr=<attr_pattern_1>&ftr=...
          Order of query params is not important.
pattern : * | name[.*], where name is a path expression
descript: removes all records with attributes matching the
          attribute pattern(s). Referential integrity constraints
          will cause records of tables where those attributes are
          foreign keys to be removed as well. If no feature
          in DB matches a pattern, no record will be deleted
          (200 OK will still be returned). If the error code
          401 is returned then none of the attributes matching
          the request pattern(s) has been deleted. Can be used
          to initialize the Personal Mode DB, by deleting all
          data in tables (note that table'num_data' are not affected, however).
example : pers?clnt=name|pass&com=remattr&attr=lang.*&attr=gender
          pers?clnt=name|pass&com=remattr&attr=*  (deletes everything from DB tables)
returns : 200 OK, 401 (fail, request error), 501 (fail, server error)
200 OK  : in this case the response body is as follows
          <?xml version="1.0"?>
          <?xml-stylesheet type="text/xsl" href="/resp_xsl/rows.xsl"?>
          <result>
          <row><num_of_rows>number of relevant rows</num_of_rows></row>
          </result>
comments: the reference to the xsl file allows to view results
          in a web browser. In case the response body is handled
          directly by an application and not by a browser, this
          reference to xsl can be ignored.