Index-calculator

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* new project HYRAS
* ignore time-dependent data variables other than input variable

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* new projects E-OBS and ERA5 included

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* add input format and component information to index_calculation.pjson

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* add grid mapping if necessary

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* new indices:

* CSf (Number of cold spells)
* HSf (Number of hot spells)
* HSx (Maximum length of hot spells)
* SD (Number od snow days)
* SCD (Snow cover duration)
* Sint (Snowfall intensity)
* Sfreq (Snowfall freqeuncy)
* UTCI (Universal Thermal Climate Index)

* add time bounds
* index-calculator version in DRS

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* split output files into several files
* restructuring time encoding
* properties removed