This class manages conversion from R2 to R3 and vice versa
To use this class, do the following:
- provide a stream or path (file or URL) that points to R2 definitions (from http://hl7.org/fhir/DSTU2/downloads.html)
- provide a stream or a path (file or URL) that points to the R3 definitions (from http://hl7.org/fhir/STU3/downloads.html)
- provide a stream or a path (file or URL) that points to R2/R3 map files (from http://hl7.org/fhir/r2r3maps.zip)
- call convert() (can call this more than once, but not multithread safe)
