Try all parts of a compound filetype

[taw10]

My Neovim setup uses a compound filetype such as scheme.guile, which is documented in :h 'filetype' as follows:

	|FileType| |filetypes|
	When a dot appears in the value then this separates two filetype
	names.  Example:
		/* vim: set filetype=c.doxygen : */
	This will use the "c" filetype first, then the "doxygen" filetype.
	This works both for filetype plugins and for syntax files.  More than
	one dot may appear.

This distinction is important, amongst other things, so that Conjure select the correct client for the particular dialect of Scheme. However, currently, nvim-paredit chokes on this, even though a valid configuration for scheme is available (I am using nvim-paredit-scheme), because get_language_api cannot find the right entry in langs. A nil value is returned, which trips up the other procedures like this:

E5108: Error executing lua ...ck/paqs/start/nvim-paredit/lua/nvim-paredit/api/wrap.lua:15: attempt to index local 'lang' (a nil value)                
stack traceback:
        ...ck/paqs/start/nvim-paredit/lua/nvim-paredit/api/wrap.lua:15: in function 'find_element_under_cursor'
        ...ck/paqs/start/nvim-paredit/lua/nvim-paredit/api/wrap.lua:65: in function 'wrap_element_under_cursor'
        /home/taw/dotfiles/config/nvim/init.lua:190: in function 'fn'
        ...tart/nvim-paredit/lua/nvim-paredit/utils/keybindings.lua:13: in function <...tart/nvim-paredit/lua/nvim-paredit/utils/keybindings.lua:12>

This change splits the filetype on ., and tries every component until it finds one with a valid configuration. For me, this fixes the problem and allows the scheme configuration to work with scheme.guile as the filetype.

[julienvincent]

Cool, thanks for the contribution!