support ggplot style figures for stats command

[lpantano]

Generate a plot like this:

from a file that looks like this:

https://github.com/miRTop/mirtop/blob/master/data/examples/plot/example_count.tsv

Libraries to use:

• https://seaborn.pydata.org/examples/color_palettes.html
• https://github.com/yhat/ggpy

The code can be added as a script under scripts folder where a function get a file with a similar content that the previous one. The function should generate a similar figure than the example.

After a function like that is implemented, the next step is to integrate in command line:

A new option in stats subcommand like --plot should generate a plot showing the difference between GFF files.

For instance, in this example:

cd mirtop/data
mirtop stats -o test_out example/gff/correct_file.gff

if we add --plot it should output the previous figure.

For that, it has to be implemented code at https://github.com/miRTop/mirtop/blob/dev/mirtop/gff/stats.py#L29.

The output of that function contains _count and _sum category. There should be a plot for each of that.

[lpantano]

Maybe @franpantano is interesting in doing the first part?