Recode approach to simple types to use explicit wrapper classes.

ADD New types package to contain AMF0 type specific or related classes.
ADD AMF0Date, AMF0LongString,AMF0Number,AMF0Reference, AMF0String, AMF0XMLDocument wrapper classes.
ADD New interface that marks the new type wrapper classes as such.
MOD Move AMF0TypeMarkers class to new types package.
ADD New package level Javadoc for types package.
MOD Update code and Javadoc in AMF0EncodingBuilder and AMF0SimpleOutputStream to use new type wrappers.
MOD Update unit tests for AMF0EncodingBuilder to use new type wrappers.
REM NoCodecAssociationException and the exceptions package, as the new approach to complex types will employ wrapper types.