TODO

Primary:
- Finish attributes fixing

Secondary:
- Rename all classes so that they're in the namespace HTMLPurifier_*
- Factor out all classes into their own files
- Build an automated release system that will create minimal versions too
- Build system that will in-line includes
- Set up the file includes
- Migrate all unit tests to use the lexer and generator
- Build the entity lookup table

Code issues:
- Factor PureHTMLDefinition into a set of strategies
- Create a TokenFactory to prevent really long lines
- Fix the encoding problems in the lexer and generator