Treat '-' as an word character in lisp

'-' is part of identifiers in most or all lisps.

Strategy for implementing this copied from https://github.com/mawww/kakoune/blob/master/rc/filetype/scss.kak#L20.

rc/filetype/lisp.kak

@@ -16,6 +16,7 @@ hook global WinSetOption filetype=lisp %{
 
     hook window ModeChange insert:.* -group lisp-trim-indent  lisp-trim-indent
     hook window InsertChar \n -group lisp-indent lisp-indent-on-new-line
+    set-option buffer extra_word_chars '_' '-' 
 
     hook -once -always window WinSetOption filetype=.* %{ remove-hooks window lisp-.+ }
 }