Compute Shannon information; Sort according to -down

[birchb1024]

• Compute the information content of each field value in the hierarchy.
• print the info content after each line
• sort the branches up or down as specified by -order

Reter to wikipedia for defintion of information content https://en.wikipedia.org/wiki/Information_content

[birchb1024]

This being experimental, it should be tried in Lua first.