Try polishing up iflib manpages a bit (basically all the low hanging fruit)

Try polishing up iflib manpages a bit (basically all the low hanging fruit)

igor:
- Fix typos.
- Delete trailing whitespace.

manlint:
- Use .Fo/.Fc/.Fa when describing functions.
- Use .Xr.
- Fill in SEE ALSO section.
- Fix .Dt use: the section was specified incorrectly and the name
  had a lowercase character.
- Continue new sentences on new lines.

Miscellaneous:
- Remove unnecessary quotes around "SEE ALSO" section headers.
- Sprinkle .Dv use in spots with constants.

Reported by:	igor, make manlint
Sponsored by:	Dell EMC Isilon