Add output log file for `cues`

[noemifrisina]

Currently cues only prints out the results of the inspection on the terminal, Mark W mentioned it would be nice to have the possibility to save this information.

• Add a -o option to the parser.
• Save a copy of the printed out cues output in a log file.

In the first instance, it's probably just enough to open a file in a context message and write the printed out lines to it.
But, this might also be a good starting point to look into adding a bit of logging to the code (see #30 ).