release_1_8 branch created

[Joshua Root]

A branch has been created in svn for MacPorts 1.8.x releases:

<http://trac.macports.org/browser/branches/release_1_8>

This means that now is the time to start committing riskier changes to
trunk. At this point, bug fixes should be merged into the branch only if
they are low-risk or fix a regression.

A 1.8.0-beta1 release has also been tagged, and an announcement will be
sent to macports-users about that soon.

- Josh