Add glossy flag theme

I'm not going to overwrite the flags currently in the repos, especially not this close to release. However, for Language Icons 6.x-2.x, I'd like to implement a feature that'll allow the module to ship with several sets of icons. "Plain" ones like now, flags from Famfamfam, and possibly yours and/or other royalty free sets.

See also: #292865: famfamfam flag icons

1. New features go into new development tree, which will probably open on September 10th (see my mail to the translator's mailing list).
2. This issue is not the one marked "feature request", so the patch does not belong here. Either add it to the previously referenced issue or, even better, open a new issue ("feature request") for it.

1. Any good reasons for not looking at the patch before Sept 10th?
2. The glossy flag theme is included aswell, so in fact it does belong here.

1. Yes, I don't want to add (or alter) any strings (see mail to translator mailing list), unless any "buggy" ones are found (again, see previously mentioned mail). In addition to this string freeze, I'm also considering the code to be in a code freeze. All in all, I don't want to look at anything pertaining to 6.x-2.x, before development of 6.x-2.x is actually open, so that I know what 6.x-2.x code will be like, and so that I can actually check in patches that are ready.
2. This issue was originally added to add a set of icons, not the functionality needed to seamlessly switch between the various provided sets. As said, making a new issue for this (and setting the famfamfam issue back to task) would be preferable.

Also, per #2: I like to keep things one issue per issue; this one is for adding the glossy flag icons, the famfamfam one is (or should be) about adding the famfamfam icons... and the feature request should be in an issue all on its own. One issue per issue.

A new issue has been created for adding an icon set selector: #319966: Add flag icon theme selector