Further updates to the netstat(1) man page and usage message

- Reformat the entire man page
- Create a proper synopsis section
- Use itemized-lists to describe each flag, rather than paragraphs
- Cross-reference common flags to a 'general flags' sub-section with short
inline description of the flag
- Label 'general flags' sub-section
- Apply additional fixes suggested by wblock, brueffer, and bdrewery
- Update .Dd that got undone previously
- Change the order of the .Op Fl to be alphabetical
- Add the -i | -I interface flags to the description of 'interface
display mode'
- Fix missing parameters in man page
- Fix missing parameters in usage()
- Sync man page and usage()

MFC Note: stable/9 and stable/10 do not have -R, will need to be removed
when merged

CR:		D58
Reviewed by:	brueffer, bcr
Approved by:	wblock (mentor)
MFC after:	7 days
Sponsored by:	ScaleEngine Inc.