Visual changes on log entry pages 2

With among other things:
- Line numbers (on current page)
- Vertical separator between line number and timestamp
- Group collapsing initially handled in generated code
- Long line excerpts (deprecated readmore.js)
- URLs replaced by &lt;a&gt; links
- Remove FFW/FBW buttons from inline entries unless target is on a different page, and show them only on hover
- Fixed even/odd background colors with JS