Allow "New Member" modal to keep track of selected users between searches
When we add new members to a project through the "New Member" modal, there is a search box and, if there are lots of users, pagination.
- If we attempt to search for a user, check it, then search for another one, the initial selection is lost.
- If we use pagination at least twice, the same effect occurs (the users selected on one page are lost).
This feature could be a good addition to redmine instances with lots of users