[tokenizer] renamed _emitEntity to _emitPartial
[index] statically export Parser, Tokenizer and DomHandler
[parser] use String#search and String#substr instead of String#split

vastly improves performance of onprocessinginstruction and ondeclaration
[parser] added onattribdata and onattribend events, dropped onattribvalue
[tokenizer] enable support for decoding entities in attributes, added onattribend and onattribdata events, removed onattribvalue
[tests] added test case for entities in attributes