Overview

This PR adds support for more robust CQL and SRU query input handling:

• transform CQL queries into OGC Filter queries by implementing a CQL parser
  • CQL parser initially supports basic conditions and AND / OR logical operators
• suppress GetRecords database errors in ogc:ExceptionReport XML

Related Issue / Discussion

NA

Additional Information

This also applies to SRU query handling given SRU queries are transformed into CQL queries.

Contributions and Licensing

(as per https://github.com/geopython/pycsw/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pycsw. I confirm that my contributions to pycsw will be compatible with the pycsw license guidelines at the time of contribution.
• I have already previously agreed to the pycsw Contributions and Licensing Guidelines