Tagger colorizer nits.

Other functions allow stripped tag text, we must here too.
If two color names occur right in a row, ensure they both count.
Tag improvements, especially for comment tags.

- Comment tags are sorted.
- Comment tags with color names color the comment.
- Private comment tags are correctly handled.
- Editing comment tags hides tags you can't edit. (But there are
  problems here---any user who can edit a comment can completely
  change its tags.)

- "tag:any" searches for tags you can see, i.e., not other
  peoples' private tags.
- "tag:none" is the complement of "tag:any".
- "cmttag:any" is still a bit of an information leak: it will return
  a comment with another person's private tag.
- But "cmttag:none" is the complement of "cmttag:any" at least.