Trying to correct the glyphs in subreddit manager

Getting "Binary files differ" if I don't remove empty line 901.
Quick Fix: gear icon should lose hover state

The gear icon was keeping its 'hover' state if you moved over it too
quickly. Replacing 'display:' with 'visibility:' fixes it.
image -> media got missed here...
make preloading of images an option, off by default, for better performance
linter fixes