libplist: Update to 1.10, enable Cython bindings

* Added HEAD
* Update to version 1.10 from 1.8
* Removed unnecessary `CMakeLists.txt` patch (now done via options)
* Removed other now unnecessary patches
* Added `--python` option for Cython Python bindings
* Added Caveat
* Added fix for CMake from `opencv.rb`
* Removed `libxml2` dependency, provided by OS X

Related to #18396

Hope the `libxml2` part is ok. I read [here](https://github.com/mxcl/homebrew/wiki/Acceptable-Formulae) that it's ok to use `depends_on` in this case, but also [here](https://github.com/mxcl/homebrew/wiki/Formula-Cookbook) that homebrew tries not to duplicate dependencies.


PS: The new binary is called [plistutil](http://cgit.sukimashita.com/libplist.git/commit/?id=1eb804e3a2a7e39771deb4b50f38e21d500f9423)