Allow toggling debug during runtime

[ydahhrk]

Currently, enabling debug messages involves a convoluted ritual that makes life difficult for everyone. I'm tired of having to shamefully ask people to perform it every time I need to provide support.

Enabling debug should be as simple as running

jool -i <instance-name> global update debug true

Disabling it should be

jool -i <instance-name> global update debug false

[ydahhrk]

I already coded this; the feature can be found in the master branch. I'm posting the issue for the sake of changelogging.

[ydahhrk]

In the end, I changed the name of the parameter to logging-debug, since Jool already had logging-bib and logging-session.

jool -i <instance-name> global update logging-debug true
jool -i <instance-name> global update logging-debug false