Allow galleries to use carousel appearance in the thumbnail "expanded mode"

[postmastersteve]

Currently, gallery styles have mutually exclusive "type" options:

• standard (slider)
• carousel strip
• thumbnail grid

Thumbnail grid supports an "expanded mode" which shows a selected photo in a large overlay viewer in the browser, but this only supports single-image viewing right now.

Proposing that the expanded mode offer carousel appearance options so a continuous strip of images can be presented instead, as some other WordPress gallery plugins offer.

[postmastersteve]

+1 Pete Bartlett ticket 190189