Pyxform

* Accept more empty rows before stopping by yanokwa in https://github.com/XLSForm/pyxform/pull/621
* Add initial support for entity creation by lognaturel in https://github.com/XLSForm/pyxform/pull/624

* avoid processing vast empty areas of buggy / strange workbooks by lindsay-stevens in https://github.com/XLSForm/pyxform/pull/612

* https://github.com/XLSForm/pyxform/pull/578 Add a lexer to identify dynamic defaults in expressions vs. strings
* https://github.com/XLSForm/pyxform/pull/607 Fix survey json->xml round trip not working for some question types

* https://github.com/XLSForm/pyxform/pull/577 Add value and label params to select_.._from_file
* Lindsay Stevens lindsay-stevens (ODK)
* https://github.com/XLSForm/pyxform/pull/594 Add support for geojson external files
* Hélène Martin lognaturel (ODK)
* https://github.com/XLSForm/pyxform/pull/596 Use read-only openpyxl representation to reduce memory usage
* Hélène Martin lognaturel (ODK)

* Improve xml hierarchy test methods, refactor test_trigger.py tests to use them by lindsay-stevens in 570
* Use openpyxl for XLSX files; upgrade xlrd to v2 by sheppard in 575
* Add support for Python 3.9 by lindsay-stevens in 580
* Warn when languages are missing translations by lindsay-stevens in 571
* Add accuracy parameters for geopoint by lognaturel in 586

* 545 Add allow-mock-accuracy parameter
* Callum Sott seadowg (ODK)
* 560 Add default value support for image questions
* Vincent Buscarello KeynesYouDigIt
* 559 Avoid recursion depth error for label with many references
* Lindsay Stevens lindsay-stevens (ODK)
* 548 Add test methods to check xml hierarchy
* Lindsay Stevens lindsay-stevens (ODK)
* 562 Clean up dependencies, remove py2 code, remove py3.6 support
* Lindsay Stevens lindsay-stevens (ODK)