Add more vim API, message accessor fns

Author: jebberjeb

src/neovim_client/message.clj

@@ -51,5 +51,5 @@
 
 (defn params
   [msg]
-  {:pre [(request? msg)]}
+  {:pre [(or (request? msg) (response? msg))]}
   (last msg))

src/neovim_client/nvim.clj

@@ -29,6 +29,7 @@
 (defvim buffer-get-line "buffer_get_line" buffer line-num)
 (defvim buffer-line-count "buffer_line_count" buffer)
 (defvim buffer-get-name "buffer_get_name" buffer)
+(defvim buffer-get-var "buffer_get_var" buffer var-name)
 (defvim buffer-set-line "buffer_set_line" buffer line-num line)
 (defvim vim-call-function "vim_call_function" f-name args)
 (defvim vim-command "vim_command" cmd-str)