ANN: Trident 1.4 Release

[chum...@gmail.com]

We are happy to announce a new release of Trident, version 1.4.  Trident is an extension of yt for the analysis of numerical datasets pertaining to the circumgalactic medium and intergalactic medium.  This new version contains a few new features and some bug fixes described below.  We highly recommend updating old versions of the code to this new version following our installation instructions.

Most notably, this new version updates the code base to help correct for a longstanding bug in yt's treatment of particle-based datasets.  These bugs led to under-accounting of fluid fields in the yt ray and Trident Lightray classes, and to a lesser extent in column density projections using the ProjectionPlot interface in yt.  These bugs only affected yt's treatment of particle-based frontends like Gadget, Gizmo, AREPO, EAGLE, etc., and had zero impact on grid-based frontends.  Fixes for these bugs were provided in yt by some truly magnificent sleuthing work by Nastasha Wijers and were merged into yt's stable version 4.4 last fall.  By updating to the most recent Trident (either stable or development), you'll incorporate these bugfixes in Trident and yt. 

For more discussion surrounding these changes or upcoming development, please feel free to join our mailing list or slack channel (links on github page: https://github.com/trident-project/trident).  We have a lot of development planned for the code in the next several months, so expect another code release soon.

Cameron

New Features
- Add calculate_ion_fraction() function for simple values and arrays. (PR 204)
- Allow option for empty rays to not raise errors. (PR 208)

Bug Fixes
- Fix yt ray bug for particle-based datasets. (yt issue 4781) (yt PR 4783)
- Fix yt ProjectionPlot bug for particle-based datasets. (yt issue 4788) (yt PR 4939)
- Do not limit number of components detected in absorption_spectrum_fit. (PR 195)
- Update commands to address yt deprecations. (PR 201)
- Fix “output array is read-only” bug. (PR 202)