Ouranosinc/xclim: v0.26.0

Announcements xclim no longer supports Python3.6. Code conventions and new features from Python3.7 (PEP 537) are now accepted. New features and enhancements core.calendar.doy_to_days_since and days_since_to_doy to allow meaningful statistics on doy data. New bias second-order adjustment method "ExtremeValues", intended for re-adjusting extreme precipitation values. Virtual indicators modules can now be built from YAML files. Indicators can now be built from dictionaries. New generic indices, implementation of clix-meta's index functions. On-the-fly generation of climate and forecasting convention (CF) checks with xc.core.cfchecks.generate_cfcheck, for a few known variables only. New xc.indices.run_length.rle_statistics for min, max, mean, std (etc) statistics on run lengths. New virtual submodule cf, with CF standard indices defined in clix-meta. Indices returning day-of-year data add two new attributes to the output: is_dayofyear (=1) and calendar. Breaking changes xclim now requires xarray>=0.17. Virtual submodules icclim and anuclim are not available at the top level anymore (only through xclim.indicators). Virtual submodules icclim and anuclim now provide Indicators and not indices. Spatial analog methods "KLDIV" and "Nearest Neighbor" now require scipy>=1.6.0. Bug fixes from_string object creation in sdba has been removed. Now replaced with use of a new dependency, jsonpickle. Internal Changes pre-commit linting checks now run formatting hook black==21.4b2. Code cleaning (more accurate call signatures, more use of https links, docstring updates, and typo fixes)