CS is overstrict on naming of new items

The CS disallows leading numbers, and included ".", in names for new items.

Given the addition of filtering in the CS, it's no longer so useful (starting names with a numeral brings these items near to the top of the list to make them easier to find). But it would be good to fix this, for compatibility with vanilla.

(RM-4062 from redmine: created on 2017-09-02 by Loriel 2, , closed on 2017-09-02 by nobody)