Update README.txt

We're somewhere else now.
Merge remote-tracking branch 'me/correct-channel'
Add just enough setup for ExampleGame that it can be installed into the
same virtualenv.
Get ExampleGame into the mix by "installing" it instead of by hacking PYTHONPATH.
Merge pull request #51 from exarkun/examplegame-setup.py

ExampleGame setup.py
Switch Link and Path to characteristic to get sane comparison and hashing behavior.
Add Path.eachSubPath.
Link to github issues instead.
Get rid of this other obviously broken link as well.
Merge pull request #58 from exarkun/issue-tracker-link-57

Fix README links
Merge pull request #56 from exarkun/eachsubpath

Add Path.eachSubPath