get doc version via installed distribution
add manpage stuff
rewrite Makefile
update changelog to reflect latest changes
Isso requires SQLite 3.3.8 or later
add target to generate Isso's CSS
extend installation docs

* add interludium for users new to Python
* include guides for prebuilt packages and building from source
  (obsoletes DEVELOPMENT.md).
store session-key in database (once generated on db creation), #74

Store a random session key used to sign and verify comment ownership
once the database is initialized, not on every application startup.

Currently fixed session keys in [general] session-key are migrated into
the database on startup. The configuration parser will notice you about
the change and suggest you to remove this option.
fix visual update up/downvote
exit if no website(s) are configured and remove default host
remove warning when SMTP is not configured as notifcation backend
Merge branch 'doc-improvements'