1. Change default variable assignments at the top to comments (two of
them were assigning empty default values).
2. Move the default for _enable to below load_rc_config
3. Add the _ifaces and _server options to command_args which eliminates
the need for the precmd
4. s#/usr/local#%%PREFIX%%#
We have not checked for this KEYWORD for a long time now, so this
is a complete noop, and thus no PORTREVISION bump. Removing it at
this point is mostly for pedantic reasons, and partly to avoid
perpetuating this anachronism by copy and paste to future scripts.
