Copy and Paste Alts

[Keltron3030]

As an achievement developer I would like to be able to copy and paste one or more alt groups to speed up development for achievements that require many similar alt conditions.

Equally useful would be the ability to copy one achievements into another like the "clone" feature but for unofficial. This of course would be irrelevant if unofficial achievements could be removed since the above feature is only needed to avoid creating excess unofficial achievements via clone>commit.

[eldexterr]

I think that's mostly the reason I evade to use a lot of alts, is kind of tedious to handle an achievement with a lot of them