Add highlight group for parentheses

[tyok]

Hi,

I tried adding a highlight group for parentheses and so far it's been working.

I have to remove a line because methods with only keyword arguments didn't behave properly:

User.where("name = :name", name: "John") # The parens gets highlighted as expected
User.new(name: "John")  # The parens didn't get highlighted
User.new( name: "John") # Strangely, this works fine

I tried to find out if the removed line will break anything, but nothing so far. I think it was supposed to prevent highlighting some symbol name as keyword (0e58499), but I have checked that it's still working without that line. I probably should mention that I don't understand what the regex means.

Please tell me if there's a better way. Thanks for your time.