Created two configs to allow use of logarithmic scale in each axis

[douglasdc]

I create two config, using the existent code in the graph base view, to allow set logarithmic scale in each axis.

logarithmic - Existent option, who still maintained
x_logarithmic - To scale X axis to logarithmic independent
y_logarithmic - To scale Y axis to logarithmic independent

hierarchy of options:
logarithmic > x_logarithmic > y_logarithmic

Was one feature how i needed. The project is so much good to use with reports, the svg charts have an small size, great to files for printing purposes.

[megahall]

@douglasdc do you have a version of this which only adds the log feature and no other changes?

I cannot tell which of these commits are required to make the feature work and which are other formatting changes. In particular, "update line graph right legend", "stroke width", and "guide stroke color"... are those something else or are they required?

It seems that "flake8 fails done" and "..." are not needed for the feature but it is hard to be sure.