Based off of instructions from http://codesanch.tumblr.com/post/1489753647/to-get-ctags-working-with-scala-and-vim
Expanded regex to handle modifiers as defined by Scala Language Specification and modified tag regex to attempt to match select operator characters between \u0020 and \u007F
Note, I took no care to validate that the modifiers are only used in the proper context (e.g. lazy should not be used with classes). This is meant to extract tags, not validate syntax so there's no gain in that additional level of pedantry.