doc(man): fix cut off page names by switching to modern asciidoctor

Asciidoc is the old reference implementation in Python, which has some shortcoming. Specifically we are hitting cut off page names for long subcommands. Fix this by switching to a more modern implementation named asciidoctor.

During the migration, get rid of the explicit asciidoc.conf file that was required to define a linkman macro, which is now supported out of the box.

Fixes #170 (closed)

Signed-off-by: Levente Polyak anthraxx@archlinux.org