expanded input date range for mixed sampling data handler (will not expand target date range and therefore sampling date range, but reduced data loss)

Resolve "Mixed sampling types"

See merge request toar/mlair!182

path inside a data handler is more often parsed as arg to enable further inheritance adjustments, data handler data is now stored separatly from the raw data location and inside experiment, data_path lost sampling attribute (is added by the handler itself),

Resolve "KZ Filter creating additional dimension"

See merge request toar/mlair!177

Merge branch 'lukas_issue202_refac_transformation-setup' into 'lukas_issue195_feat_kz-filter-dimension'

Resolve "REFAC: transformation setup"

See merge request toar/mlair!181

introduced two new concepts DataClass and TransformationClass to set transformation for inputs and targets independently

new data handler using kz filter (not fully completed), there went something wrong in the spectral calculation but is fixed now, tests still missing, updated xarray version

* corrected own_args method
* corrected workflow registry
* renaming of all data_preparations to handlers
* data handler can use class data_handler attribute
* error handling in post processing

Master2Dev

See merge request toar/mlair!172

Resolve "bug: too many indices in PlotClimatologicalSkillScore"

See merge request toar/mlair!167

Resolve "bug: dist file not included in v1.0.0"

Closes #190

See merge request toar/mlair!165

Resolve "new release v1.0.0"

Closes #188

See merge request toar/mlair!162

update release branch by recent developments

See merge request toar/mlair!164

another update

See merge request toar/mlair!163

replaced xargs by standard pip install for all steps it is not required (keep only for tests from scratch) to save time

cartopy 0.18 has problems when installing numpy at the same time, change to xargs installation (line by line pip install)