support for videos from niconico douga (nicovideo)

[lalondeguy]

describe the feature you'd like to see
title, would like to be able to download videos from niconico douga.

describe alternatives you've considered
afaik there aren't any other sites that let you download videos from it, so... none? (idk though)

additional context
idk about anyone else, but the site is pretty important to the vocaloid community as a lot of vocaloid songs are only posted there, being able to easily download videos from it would help a lot with preserving and reprinting them

[dumbmoron]

duplicate of #60, pending pull request: #510