options: deprecate 'lua' based options/dirs for 'script'

- --lua and --lua-opts change to --script and --script-opts
- 'lua' default script dirs change to 'scripts'
- DOCS updated

- 'lua-settings' dir was _not_ modified

The old lua-based names/dirs still work, but display a warning.

Signed-off-by: wm4 <wm4@nowhere>
vo_opengl: remove quadbuffer/anaglyph stereo 3D rendering

Obscure feature, and I've never heard of anyone using it.

The anaglyph effects can be reproduced with vf_stereo3d. The only thing
that can't be reproduced with it is "quadbuffer", which requires special
and expensive hardware.
scripting: fix/improve deprecation message

The message was missing a '\n', so it was merged with the next line,
which also typically caused it not to be printed with the colors for
warnings.

Print the full new path in the warning message. (Normally, cfg should
never be NULL, so accounting for this case is just for robustness.)