Update manpage: Add Firewire backend options & more (#300)

* update manpage: add Firewire backend options

additions:
-firewire backend options
-note about JACK name
-links to JACK github page, mailinglist, ffado.org
-manpage author
-note about how to create pdf from manpage

removals:
-dead/unavailable links

formatting:
-remove double spaces after '.'
-all urls are bold, enclosed in <>, ending with / if it's not a file
-(non-printable) empty lines between sections for better overview

other:
-partial rewording of main paragraph. misc small changes (see diff).

* typo

* use ',' everywhere to list short/long options

* Unify indication of default values.

* More backend unification (remove 'specify ..')

* -1 typo