Replace references to pkg_add with pkg install
Replace links to pkg_add man page with links to pkg-install
Remove references to manually downloading packages, or specifying an ftp url
Remove link to pointyhat that no longer resolves
Update the svnweb link to point directly to the ports tree
use &base; entity everywhere
Use https where applicable

PR:		193370
Reviewed by:	gavin
Approved by:	bcr
Sponsored by:	ScaleEngine Inc.
CR:		D732
Replace all occurances of 'pkgng' with 'pkg' in the handbook
Kept existing xml:id's to avoid breaking external links to the documentation
Sanitized the documentation of references to pkg_add
Fix an incorrect variable name: daily_backup_pkgng_enable should be daily_backup_pkgdb_enable
Fix a linebreak in the middle of a variable name
Clarify that pkg2ng is not a required step on newer systems

Approved by:	bcr
Sponsored by:	ScaleEngine Inc.
Remove the portbuild article - it is entirely out-of-date and would need
a complete rewrite in order to update it for the new port building world
using poudriere.

Approved by:	bapt
Remove more references to pkg_add

Approved by:	bcr
Sponsored by:	ScaleEngine Inc.
CR:		D733