Replace the use of the internal_report structure (for reports from
engines, MPV etc) with the Rose program interpreter.
SOM processing was reworked to use a new som_operation structure that is
embedded in the appropriate instructions.
This allows sibling character classes to be merged together before graph
component splitting is done by calcComponents().
In particular, this transforms (A|a)(B|b)(C|c) into [Aa][Bb][Cc]
earlier.
