VStar version 2.21.0 released

It has been almost two years since the last release, but VStar version 2.21.0 is now available.

Most releases have been no more than a year apart, often only several months. I intend to return to a shorter release cycle.

Key Changes

• ANOVA functionality is no longer included in the File -> Info dialog. The Current Mode ANOVA plug-in must now be used.
• Heliocentric Julian Date conversion no longer happens automatically. The Heliocentric JD Converter plugin must now be used. This was a result of conversations with Sebastian Otero, Mike Miller and others. Non-HJD datasets may be selected for conversion using this plugin.
• The AID load dialog has been enhanced with numerous options including selective band loading, inclusion of observations by observer code, application of a VeLa filter to further reduce observations retrieved. Internal optimisations have also been applied. Some of this was only made possible by Patrick Wills making enhancements to the AID web service.
• Various improvements to VeLa dialog and language. See Change Log.
• New Observation Transformation Plug-in type added, with undoable edit support (undo/redo), along with two plug-ins:
  • magnitude baseline shifter
  • VeLa observation transformer
• Added support for model creation, including polynomial fit, in scripting API.
• Added getters for magnitudes, times, phases to scripting API.
• All observation source plug-ins now permit observation filtering at load-time via VeLa filter expressions.
• Support for SkyPatrol and ASAS-SN photometry database CSV by Maksym Pyatnytskyy in ASAS-SN plug-in.
• Gaia observation source plug-in created by Cliff Kotnik.
• Flexible File Format observation source plug-in created by Maksym Pyatnytskyy.
• Creation and update of documentation for HJD converter plugin, Hipparcos, DASCH and ASAS observation source plug-ins, Loess model and AoV period analysis plugins. 
• Created an Observation Sink plug-in category and converted internal file saving to use this. Possible future observation sink plugins: save as Upload file format, XML.
• The first cut of a VeLa model creator plug-in was written.
• The Kepler plug-in was extended to handle TESS by Cliff Kotnik and Maksym Pyatnytskyy.
• A preference was added to allow the user to decide whether file/URL-based observation source plug-ins should all appear in File menu or whether they should appear in “New Star” file chooser (the new default). This currently takes effect after restarting VStar.
• The Julian Date column in the observation list and plot domain axis title changed to Time.
• There were numerous user manual updates.
• Fixed a serious bug in which some observation object data members were mutable. This is potentially problematic when such objects are cached (i.e. two observations sharing a single observation object could lead to changes in both).
• Fixed a problem in which AoV period search scan results were being dropped early in the range.
• Fixed a bug in which some cached ValidObservation data members were mutable.
• Fixed a bug in which some dialogs were hidden behind the main window, e.g. mean time between selection plug-in.
• Various other minor bug fixes and improvements.

This list is by no means exhaustive. See the ChangeLog for more details and for the related tickets:

    https://sourceforge.net/p/vstar/code/HEAD/tree/tags/DEV-AAVSO-03May2020/ChangeLog.txt#l36

Thanks in particular to Cliff Kotnik, Dave Hinzel, and Maksym Pyatnytskyy (Max) for all their work towards this release and to Sara, as always. Bert Pablo made the good suggestion of creating a Slack channel for VStar which we have put to good use. Cliff and Max wrote plug-ins (with attribution given above for specific plug-ins not written by me) and documentation. Dave Hinzel wrote and reviewed documentation. All three did a lot of testing, reported bugs, and provided other feedback. Thanks to Dave and Cliff for talking the lead on testing. In addition, Patrick Wills enabled some of the AID load features via enhancements to the web service.