Allow regex for name validation

[HYDeath]

Would like to be able to implant this option into config: Match Regex pattern: [a-zA-Z0-9_]*. For example, like Authme:

[HYDeath]

Or my suggestion is to add all three options in Name Validation to the config for better customization.

[HYDeath]

@kyngs Is there any hope that this will be updated anytime soon?

[kyngs]

It will be done before 1.0.0, no ETA. The plugin is open-source, you can hire someone to implement it, or do it yourself.

[HYDeath]

@kyngs Hi, I see Pr inside this #249 , I feel that this is still quite more in line with my this, this seems to be rejected, why is it, looked at the code seems to let the Chinese go offline plus a ban on the use of the offending name, I feel that there is no problem.