Define left- and right-hand filetypes via global config variable

plugin/splitopen.vim

@@ -1,5 +1,13 @@
 command -nargs=1 SplitOpen :call splitopen#SplitOpenFile("<args>")
 
+" map left-split / right-split file extensions
+if !exists("g:splitopen_extensions")
+	let g:splitopen_extensions = {
+		\	"h": "cpp",
+		\	"H": "CPP",
+		\	}
+endif
+
 if !exists('g:splitopen_set_fzf_keys')
 	let g:splitopen_set_fzf_keys = 0
 endif
@@ -9,5 +17,6 @@ if g:splitopen_set_fzf_keys
 		\	'ctrl-s': 'SplitOpen',
 		\	'ctrl-t': 'tab split',
 		\ 	'ctrl-x': 'split',
-		\ 	'ctrl-v': 'vsplit' }
+		\ 	'ctrl-v': 'vsplit',
+		\	}
 endif