Rewrote parseTagLine; now correctly parses ctag lines with "/^" in the name section

The regex used in the original parseTagLine would sometimes encounter problems parsing lines which contained "/^" in the name field, before the filepath, such as when parsing Readme.md in https://github.com/busterjs/formatio ### `excludeConstructors (["Object", /^.$/])`

I've rewritten the function in a way which I hope will parse more consistently.

This is my first pull request, so I'm sorry for any mistakes!  I hope you'll fix the bug either way!