fix bug in process feed service

Deduplicating some logic and switching to pluck, to avoid pulling the entire model in memory.

h-feed, h-card and h-entry

for local attachments, use them in URLs. Check status privacy
before redirecting to actual file.

This allows other platforms such as Windows, macOS and iOS to use their system fonts rather than downloading a copy of Roboto. It also makes the app feel a little closer to native on those platforms!

The "settings" links in the Getting Started section (or, if #399 were to happen, "more" menu) and compose sections are now different; the "compose" link is "Edit profile," while the one in the Getting Started section is now "Preferences."

All languages have been updated to accommodate this, based on the existing usages of these phrases in language files in the Rails part of the app!

addresses part of #384

Don't ask users to check the console - if they're on mobile, they probably can't anyway ;)

metaKey is only set correctly on keyDown, not keyUp, so this swaps to using that