Improve many implementation by using stdlib maybe function
Improve requireAttrRaw using maybe similar to ignoreAttrs
Improve ignoreAttrs implementation using const
Simplified orE using maybe
Simplified choose
Simplified force using maybe
Use maybe to implement optionalAttrRaw
Use maybe to improve decodeHtmlEntities implementation
Use either to simplify instance Alternative AttrParser
Use either to simplify instance Monad AttrParser
Use either to simplify push in detectUtf
Merge pull request #39 from ulikoehler/simplifications

Stream parser: Simplified implementations using either & maybe
Added tagIgnoreAttrs
Added manyIgnore (prototype)
Added tagPredicateIgnoreAttrs
Added ignoreTag & ignoreTagName
Added ignoreAnyTagName
Added ignoreAllTags
Added tree ignore prototypes
Fix ignoreTree