Pyxform

* 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)

* 547 Fix parsing of (multiple) pulldata calls in a (multi-line) expression
* Lindsay Stevens lindsay-stevens (ODK)
* 545 Do not warn about labels when using an unlabeled groups
* Yaw Anokwa yanokwa (ODK)
* 544 Levenshtein distance warning for sheet name misspellings
* Lindsay Stevens lindsay-stevens (ODK)
* 543 Output empty label instead of omitting it
* Lindsay Stevens lindsay-stevens (ODK)
* 541 Fix windows test failures related to temp file creation by Validate
* Lindsay Stevens lindsay-stevens (ODK)
* 540 Remove Java version check
* Lindsay Stevens lindsay-stevens (ODK)

* 535 Don't check for dynamic label if there is no label
* Hélène Martin lognaturel (ODK)
* 536 Expand refs in predicates using current() even if preceded by whitespace
* Agus Hilman gushil (OpenClinica)

* 521 Use itext for dynamic selects with dynamic labels
* Agus Hilman gushil (OpenClinica), Hélène Martin lognaturel (ODK)
* 522 Add support for csv-external
* Hélène Martin lognaturel (ODK)
* 526 Warning for dynamic defaults now more annoying than helpful
* Yaw Anokwa yanokwa (ODK)
* 524 ${} references in predicates should be expanded using current()
* Agus Hilman gushil (OpenClinica)
* 529 Apply section name check to sections only
* John Milner jnm (KoBo)
* 516 Generate correct reference when selecting choices from current repeat question
* Davis Raymond DavisRayM (Ona)

* 514 Fix circular reference error raised when converting an XLSX form with multiple languages to JSON
* Davis Raymond DavisRayM (Ona)
* 519 Add support for odk:recordaudio
* Callum Stott seadowg (ODK)