Add function for preparing emission time series, fitting annual emissions and comparing with true values

Add function for checking for realistic gradient in plume coords; use shortest arc length instead of shortest distance from curve for computing across-plume coords

Update plot function; new parameters for providing varnames; new parameter to use error when fitting and fixed uncertainty computation

Use xarray.Dataset to store data from within polygon and the function for showing it to the vis module

Add background module and moved code from gauss module
Add code for filling small data gaps due to clouds before doing mass-balance
Re-structure code for processing more data

Remove old code not used anymore
Add function for reading mass-balance results from SMARTCARB Version 1
Add function for reading all time series of estimated emissions for
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