Additions:
- New Extra Arguments system for objectives. You can append as many of them as you like at the end of objective creation commands.

I've added the first two extra arguments to the KillMobs objective, which are " nametag_containsany" and " nametag_equals".

Example:
This will only accept kills of zombies who have the name tag "bob the killer". It's case-insensitive.

If you use "nametag_containsany" instead of "nametag_equals" it would also match zombies with the name tag "bob the great killer" or "[4] bob the killer" if you got a level before the name — as long as every of the words separated by spaces is in the name tag. It's case-insensitive as well.

Might be interesting for you @honla