Adding fixmes

In this branch, I looked for entries that were empty or had FIXME as their only content, and wrote some content for them.

I also added some questions that struck me as good ideas: GPG development, defining the term 'keyserver', expanding the strong_passphrase question, copying the automated_use question from the old FAQ, etc.  Please

(IMPORTANT: note that this branch is atop my akuchling-fixes branch, so you probably don't want to just merge it.  It does have the controversial commit from akuchling-fixes removed, though.)