I am having second thoughts about overloading the tag system with
"from:delicious", "from:twitter" and so on. Instead, I will add an
origin field to the bookmarks table, so the information is preserved
without polluting anyone's tag cloud.
For the time being, I'd appreciate it if you left the from: tags in
place, so I can properly update the origin field when I fix things
up. I'll nuke the various from: tags once that's ready.