move unused xquartz.rb to new namespace

* migrate methods app_with_bundle_id and pkgutil_info within xquartz.rb
  as this is the only place they are used
* remove duplicate X11 namespace
separate hardware from MacOS

and remove unused method prefer_64_bit?
merge all OS X release symbols into one file
recast class OS::Mac::Version as OS::Mac::Release
cache inverted Release hash
make @@release a class variable
incorporate homebrew-fork OS::Mac as Cask::MacOS

temporarily define ::MacOS = Cask::MacOS pending updates
to the DSL (it should be visible at the top level only
within Casks.)
Merge pull request #8539 from rolandwalker/incorporate_homebrew_macos

incorporate a modified homebrew-fork `OS::Mac` into our codebase as `Cask::MacOS`