port -e, environment mode

[pixilla (Bradley Giesbrecht)]

Add a new port short arg "e" to print env info useful for support.

$ port -e version
--->  prefix: /opt/local
--->  portdbpath: /opt/local/var/macports
--->  applications_dir: /Applications/MacPorts
--->  frameworks_dir: /opt/local/Library/Frameworks
--->  sources_conf: /opt/local/etc/macports/sources.conf
--->  variants_conf: /opt/local/etc/macports/variants.conf
--->  universal_archs: x86_64 i386
--->  sources_conf: file:///Users/brad/misc/bitbucket/pixilla/macports/dports nosync
--->  sources_conf: file:///Users/brad/misc/macports/users/pixilla/dports nosync
--->  sources_conf: file:///opt/local/var/macports/sources/svn.macports.org/trunk/dports default
--->  variants_conf: +bash_completion
--->  PATH: /Users/brad/bin:/Users/brad/misc/macports/users/ryandesign/scripts:/Users/brad/misc/macports/users/pixilla/scripts:/opt/local/apache2/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
Version: 2.0.99