FIX: apply correct decoding of VEL, WIDTH and KDP in IrisCartesianProductFile

ENH: add STATUS product to Iris/Sigmet reader

FIX: use LooseVersion to check for dependency matching and issue issue warnings, remove explicit dependency requirements in requirements.txt (#414)

MNT: Rel 1.6.0

Pre 1.6.0 fixes (#412)

* DOC: revise docstrings in io.xarray
* MNT: update travis/install.sh
* MNT: remove caching, trigger rtd only once in DEPLOY
* MNT: update copyright date

ENH: fix odim moments before merge, if their shape differs

Co-authored-by: Edouard Goudenhoofdt <egouden@users.noreply.github.com>
Co-authored-by: Kai Mühlbauer <kmuehlbauer@users.noreply.github.com>

ENH: Improve azimuth reindexing, add odim/cfradial2 output to XRadVolume (#409)

ENH: Improve azimuth reindexing, add odim/cfradial2/netcdf output to XRadVolume

ENH: Rework ZR (#408)

* ENH: Rework ZR (enhanced DWD)
* ENH: make shower index output triggered by keyword

FIX: add ODIM WRAD moment, use Dataset.swap_dims for CfRadial instead of Dataset.rename

FIX: low cloud switch removes everything

FIX: correct netCDF4 requirement

FIX: add missing '+'-sign in projection string

ENH: Implement multi-file ODIMH5 reader (#397)

MNT: Set up CI with Azure Pipelines

First step to utilize Azure Pipelines [skip ci]

MNT: test GDAL2 and GDAL3 (#403)

FIX: use xarray.Dataset.rename instead of rename_dims (#402)

MNT: use semver 2.9.0, fix setup.py (#399)

FIX: use xarray `Dataset.drop_vars` instead of deprecated `Dataset.drop`

MNT: update travis

ENH: refactoring code into `assign_root`-function