Runtime kind handling for ocp-browser.

The kinds are now printed on the top right of the input windows and ALT-<FOO> toggle the <FOO> kind flag.

I had to modify ocp-indent-libs a little bit, by exposing the current kind flags and allowing to change them. We could probably go without the mutability, but this seems cleaner.
I'm not really satisfied by the records of flags, what do you think ?

There is no real documentation for ocp-browser. Where do I document this new feature ?