Changes in 1.23.1:
- Enable compression in exported files (Benjamin K. Stuhl)
- Fix saving histogram datasets
- Add option to "thin" error bars plotted
- Fix label colour in contour labelling
- Remove use of deprecated Qt functions
- Fix clone widget tools plugin
- Fix EPS/PDF crash with broken axis widget
- Do not crash filter plugin if using date datatype
- Avoid crashes in normalise, subtract minimum and divide maximum plugins
- Avoid crash in image widget
- Avoid issue in identifying spacing in 1D->2D conversion
- Add Gnuplot 2D data import plugin (Joerg Meyer)
- When loading data from import plugins, provide default values
- Remove some deprecated Qt uses
- Fix issue when plotting non-plain datasets with nan values