outdir() and variants() docs
Fix broken chunk specifier in read_ppa
Add ppa.lsm to Zresults

Results are parsed from PPA LSM results file if present
Implement $-operator for Zresults-class

Access all slots using it.
Update NEWS
Rename vignettes
Remove $-notation access from Zresults

Instead, use ppa_lsm() method
Udpate docs
Add Z color scheme spectral to .options
Update docs
Add zlegend()
Fix method rd-name
Comment out a Zvariant test

Until ppa.lsm is available in basic tutorial as well.
Add an empty dir to outputs for testing purposes
Add rank_raster() and rank_rasters()
Fix initialization of Zresults

Empty output dir caused problems
Rename results vignette

All results are demonstrated within the same vignette file.
Update group naming in vignette
Implement curves() for Zvariant
Update curves() generic documentation