add "format_description" function

[fitoprincipe]

This was a function included in the previous version of this package. The purpose of this function is to adjust any parsed string to the "description" format:

The description must contain only the following characters: a..z, A..Z, 0..9, “.”, “,”, “:”, “;”, “_” or “-”. The description must be at most 100 characters long.

This allows users to save time by not having to worry about the characters included in the description string.