Update BufExplorer to version 7.4.2.
Update manpageview to version 25l.
Adjust ManPageView settings:

- Return to default "hsplit" mode for opening man pages.
- Patch the "sleep 2" calls to become "sleep 250m" on errors.
Whitelist font families with known-good Unicode symbols.
Add a "cache tag" for detecting changes to Powerline settings.
Cleanup references to VIMRC_BEFORE and VIMRC_AFTER.
Add Powerline segment to detect trailing whitespace.
Update tags.