Steps to reproduce the original issue:
1) alerts are enabled and counter is positive
2) the user disables the alerts from preferences
3) ntopng is stopped, then restarted
4) the user enables the alerts from preferences, but num_alerts_engaged was 0
5) a release of an alert now makes the counter wrap
* Add alias and device type columns to host pools
* Add host pool members links when available
* Add host pool links
* Implement host pool members pagination
* Host Pools GUI fixes and improvements
* Remove hardcoded columns number
* Host Pools GUI fixes
* Remove debug print
ntopng checks MySQL for the value of open_files_limit and engages
and alert if the worst case number of open files is greater
than or equal to the 80% of open_files_limit
Clicking on flow details (e.g., protocol or src or dst)
automatically redirects the user to the db explorer page
and preserves selection details (pro version).
Interface flows are now stored using integer interface ids rather
than interface names. This speeds up queries.
A migration code has also been introduced so that old MySQL table
format is migrated and old data does not get lost.
This also fixes#460
Lua function that query MySQL return an empty lua table
not only in case of an empty record set, but also in case of error.
This prevents upstream iterations over nil values.
Overal Top Talkers are retrieved with just one single
MySQL query and include both ipv4 and ipv4. Top talkers
can be visualized on a per-interface and per-host basis,
and can be sliced and diced.
Top Talkers and Top applications can be retrieved via MySQL
both interface-wide and per-host. A couple of tabs, namely
"Top Talkers" and "Top Applications" become available in the
historical page of interfaces and hosts. Upon focus of each
tab, an ajax request is triggered and data is fetched from MySQL.
TODO: interface wide top-talkers are retrieved from sqlite and
need to be moved to mysql.
