Use shell-style word-splitting on `editor`
Use shell-style word-splitting on `editor`

Use `shlex.split()` on the (possibly user-provided) editor, to avoid
passing a nonsensical list to `subprocess.Popen`.

Allow use of `plugins.var.python.edit.editor = "vim -c 'set notitle'"`,
for example, which previously was passed to `subprocess.Popen` as
`["vim", "-c", "'set", "notitle'", path]`.

keith/edit-weechat