Filetype scope key bindings.

[kbenzie]

This is a feature request.

I continually reach for my formative.vim key bindings in file types which clang-format does not support. Whilst this isn't that big a problem in and of its self, it would still be convenient if the bindings where only enabled for filetypes which clang-format supports.

I can envisage a use case where you would want to keep the current behaviour, when formatting example code in documentation (although I've never done this), so it would make sense to make this feature opt [in|out].

An additional benefit is to leave the key bindings open for filetypes clang-format does not support such as a (hypothetical?) tidy plugin for html which has similar behaviour to formative.vim.