This function loads the data and adjust some wrong column types. It
shoulb be used from all other scripts to load the data. It the same
source data for all following calculations.
The data is stored inside a 'tibble' from the 'tidyverse' package.
sma_plot_file(fname, ftype, title_list, legend_list, fun, ...)
can be used to write plot to a file.
It supports all output filetypes R can handle. Title and legend
arguments can be passed as lists.
All available plotting functions can be used, arguments go into a
variable argument list.
The base data was changed from month to years for more precision.
Therefor the scaling of the graphs must be adjusted to days per year
instead of month per year.
