Allow exclude keys by pattern/regexp

[kapcod]

I have a lot of keys with invalid namespace ('_' separator instead of ':'), this lead to huge report full of these keys. I'd love to have '--exclude' parameter, ideally regexp, that would allow me to put there all problematic keys, like group of keys with non ':' separator and other like this. This way I can run report and update my exclude rule until I get only keys with normal namespace. Then after fixing namespace separator for all the problematic keys, I'd be able to re-run the test without the exclude rule and see only normal grouped keys. If it's decided to have '-exclude ' but accept matcher string with wildcards, instead of regexp, then it should allow having multiple '--exclude' parameters.