Suggestion: Lightbox supporting resizing of large images

[Valtasar]

Many of our board users had many problems viewing large images in IPB3, since the version of Lightbox used does not allow resizing them.

I tried this alternative, and works great (although maybe a bit slower),
with no code changes needed (except removing the options header) and only two extra options to be added in "include_lightbox_real" skin template.

I think it's a nice option to consider for anyone facing the same problem and maybe invisionpower could try to support this in future IPB versions.