Fixes and tweaks

This is an MR containing multiple small-ish fixes, most of them are in separate commits but some depend on previous ones.

Fixes:

• Fixed enormous emoji in username
• Fixed text vertical alignment in post header
• Fixed "open on home instance" icon not being aligned with plus sign icon.
• Fixed clickable icons in post header not having hover color
• Fixed NSFW placeholder not having pointer cursor indicating that it's interactive
• Fixed NSFW video requiring double click to hide NSFW placeholder
• Made pausing posts streaming while tab is unfocused configurable (request by @shpuld ) (default: pause when unfocused)
• Added styles for sub-options and disabled options: pausing streaming makes no sense when streaming itself isn't enabled.
• Added option not to loop videos at all (default: loop videos).
• Added option to not loop videos containing audio (default: loop only silent)
  • May not available on some browsers - depends on moz* and webkit* APIs and future spec that's not supported ATM
  • Availability is tested on settings page, option is disabled and warning is shown when option isn't available.
• Fixed lock-unlocked-alt icon being not aligned with lock icon (mostly noticeable in post form)
• Changed "delete attachment" to be outside the attachment so that it can be clicked when uploading very wide image and also to avoid overlapping it with "play" in audio/video uploads.
• Audio attachments now take full width when uploading.
• "Link" attachments generated when uploading something that is not image/video/audio or that's not recognized as such now correctly shows as link inside attachment frame
• Changed persistent state to store entire config instead of each of its properties to fix option to disable gif animation not persisting and to avoid such bugs in the future.
• Moved some timeline-related settings into separate category on settings page