Type explainer can't parse methods ending in '?' and '!' #1077
Description
It would be nice to be able to document methods as @param foo [#all?] but the type explainer currently fails on methods like this. I realize it is really hard to parse ruby methods so I'm definitely not asking for something comprehensive, but adding ? and ! would be nice.
Steps to reproduce
$ irb
>> require 'yard'
>> YARD::Tags::TypesExplainer::Parser.parse('#all?')
SyntaxError: invalid character at ?
from /Users/johnbackus/.gem/ruby/2.3.1/gems/yard-0.9.8/lib/yard/tags/types_explainer.rb:154:in `block in parse'
>> YARD::Tags::TypesExplainer::Parser.parse('#gsub!')
SyntaxError: invalid character at !
from /Users/johnbackus/.gem/ruby/2.3.1/gems/yard-0.9.8/lib/yard/tags/types_explainer.rb:154:in `block in parse'
I would be happy to do a PR fixing this