Problem:
When "-l" is followed by "--", we stop sending args to the Lua script
and treat "--" in the usual way. This was for flexibility but didn't
have a strong use-case, and has these problems:
- prevents Lua "-l" scripts from handling "--" in their own way.
- complicates the startup logic (must call nlua_init before command_line_scan)
Solution:
Don't treat "--" specially if it follows "-l".
Problem:
Nvim has Lua but the "nvim" CLI can't easily be used to execute Lua
scripts, especially scripts that take arguments or produce output.
Solution:
- support "nvim -l [args...]" for running scripts. closes#15749
- exit without +q
- remove lua2dox_filter
- remove Doxyfile. This wasn't used anyway, because the doxygen config
is inlined in gen_vimdoc.py (`Doxyfile` variable).
- use "nvim -l" in docs-gen CI job
Examples:
$ nvim -l scripts/lua2dox.lua --help
Lua2DoX (0.2 20130128)
...
$ echo "print(vim.inspect(_G.arg))" | nvim -l - --arg1 --arg2
$ echo 'print(vim.inspect(vim.api.nvim_buf_get_text(1,0,0,-1,-1,{})))' | nvim +"put ='text'" -l -
TODO?
-e executes Lua code
-l loads a module
-i enters REPL _after running the other arguments_.
