Update README.md

Frameworks/Framework
Initial pear-packaged code for Castanet.
Update package dependencies.

Remove dom dependency. This extension is provided by default with PHP.
Add Swat dependency.
Remove SwatDate dependency.

Interface is provided by DateTime which is included by default.
Use DOMTextNode to escape entities.

Allows removal of Swat dependency.
Fix class name.
Merge pull request #3 from gauthierm/initial-package

Initial pear-packaged code for Castanet.
Whitespace.
More data escaping using text nodes.
Fix syntax errors.
Merge pull request #4 from gauthierm/initial-package

Initial package cleanups
Fix a typo that prevented package from building.
Merge pull request #5 from gauthierm/fix-package-php

Fix a typo that prevented package from building.