Its coming... but certainly not today... (or tomorrow...)
For the mysql functions - I would look at the post from cheigu as a workaround - translates the mysql function calls to mysqli. I see no reason why that won't work with CPG.
For the mysql_connect support in PHP7, there is a library on http://sourceforge.net/projects/mysqlwithmysqli/ (usefull also for other projects and temporarly solutions)
cpg1.5.x has other problems with PHP7 and should not be used with it, altough the galery itself runs with the above mysql solution there are issues to solve in the admin section.
Just need to add an include for this script - adding something like this to the beginning of include/functions.inc.php:
if (!function_exists('mysql_connect')) {
require 'mysql_mysqli.inc.php'; //* adjust to correct path based on where you placed the file...
}
EDIT: actually the 'if' logic isn't required - as the included file already checks and bypasses:
if(!is_callable('mysql_query')) {
END EDIT
The plugin API isn't yet initialized when the database connection is made (it needs DB info to initialize) - so no opportunity to add this logic via a plugin..
As for other requirements of PHP7 - I don't believe we have addressed that at all as of yet. CPG 1.6 will require PHP5 as a minimum. But I know I haven't done any testing beyond that as of yet - perhaps others here have.
I don't know the specific issues that cheigu referred to.
This is certainly first I've heard of an ISP requiring use of PHP7 - most don't even have it available as an option yet - at least in shared hosting packages. I expect CPG is far from the only package that will have an issue in a PHP7 environment today.