Now that modeline are supported, they will affect the content of
version. This commits only adds the new information. `--version` has
to be the last command line argument and the modeline isn't parsed
yet.
Another commit will make sure --version parses the modeline and
finishes to process the command line arguments in case it isn't
last. Please note that luarocks also affects data points such as
the LGI version. It should be smarter and check if `rc.lua` has
`require("luarocks")`. This commit does *not* do it.
d58b4c3d96