Simplified XSD numeric data types

Replaced arbitrary-precision data types xs:integer and xs:decimal with
their limited-precision counterparts xs:int and xs:double, respectively.
Split @Schema annotation into @Added and @Removed annotations
Complete representation of all PMML schema version 3.X and 4.X documents
Un-deprecated default constructors
Added @Deprecated annotation
Extracted annotation inspection functionality into a separate base class
Replaced auto-generated Java type adapter with a hand-coded one
Renamed package