Albums scrollable and CW with blurhash

Makes scrolling in album possible on feed.

Fix some width/height setting problems (related to recyclerview shenanigans).

Get rid of the tabs for albums and use circle indicators instead.

No more special case for single-photo posts: everything uses the same viewpager-based way now.

CW-ed photos/albums now show the blurhash instead of just a black background

Closes #260 (closed)