[imp] Error with Kronolith and PHP 7

[poubeline at free.fr]

Hi All, 

I have just upgraded my Horde Webmail to the latest version and I have the following error in my logs regarding Kronolith and date format : 

| [Fri Sep 22 15:35:56.317874 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date_Holidays has a deprecated constructor in /usr/share/php/Date/Holidays.php on line 91, referer: https://<my_server_url>/kronolith/ 
| [Fri Sep 22 15:35:56.321707 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date has a deprecated constructor in /usr/share/php/Date.php on line 123, referer: https://<my_server_url>/kronolith/ 
| [Fri Sep 22 15:35:56.325672 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date_TimeZone has a deprecated constructor in /usr/share/php/Date/TimeZone.php on line 70, referer: https://<my_server_url>/kronolith/ 
| [Fri Sep 22 15:35:56.331302 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date_Span has a deprecated constructor in /usr/share/php/Date/Span.php on line 114, referer: https://<my_server_url>/kronolith/ 
| [Fri Sep 22 15:35:56.332119 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date_Holidays_Holiday has a deprecated constructor in /usr/share/php/Date/Holidays/Holiday.php on line 36, referer: https://<my_server_url>/kronolith/ 
| [Fri Sep 22 15:35:56.333058 2017] [:error] [pid 1706] [client 192.168.1.254:54176] PHP Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; Date_Holidays_Driver has a deprecated constructor in /usr/share/php/Date/Holidays/Driver.php on line 125, referer: https://<my_server_url>/kronolith/ 

Is there something to do on my server (install a new 'date' package for PHP 7)? Or is it something to change for the next release of Kronolith? 

I run a Debian Stretch server with PHP 7.1 and the latest patches. 

Thanks