Dtscalibration

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* Reduced flexibility in defining Stokes labels

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* Same as 0.9.2

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* Increased precision of least squares solver, as this was limiting theprecision of the parameter estimation
* The variance of the noise in the Stokes can change linear with the intensity
* Improved residuals plot function
* Reduced the number of equations for double ended calibration
* Support for transient attenuation due to connectors along fibers
* Matching sections

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* Valentine edition
* Added example for fixing parameters
* Bug fixed in routine for reading Sensornet files (Bor van der Scheer)
* Official support for Python 3.8
* When the datastore is printed to the screen, the mean and std of thereference temperature is plotted
* Integrated differential attenuation is reformulated. Starts integrating atthe first reference section location.
* Estimation of the variance of the Stokes that is linear dependent on theintensity (Poisson)
* Removed `__slots__` attribute

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* Update automated zenodo reference requires to draft a new release

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* Solved xlim in subplots of plot_residuals_reference_sections funciton
* Solved YAML deprecation related problems
* Introduced new approach for double ended calibration, with a different Cfor the forward and backward channel
* First code added for time variant asymmetric attenuation, such as connectors.
* First code added for matching sections