.MM file format
        ---------------

The .MM file format (short for MIDAS Module) is designed to allow fast
and simple loading of the modules, and even linking of the modules
directly to the executable file, instead of maximum flexibility or
minimum size. Therefore the file mainly consists of internal MIDAS
structures. Note, however, that in the structures the pointer values
are completely meaningless, and the file has to be processed in
sequential order, building the necessary pointers on the fly.

The file format is as following:

        mpModule        module;
        uchar           orders[module.songLength];
        mpInstrument    instruments[module.numInsts];
        mpPattern       patterns[module.numPatts];
        uchar           instsUsed[module.numInsts];

        After this follow the samples, in 8-bit delta format. All
        samples which are used (instsUsed[i] == 1) are stored as
        instruments[i].length bytes. To convert samples to raw format,
        use the following routine:

        unsigned        a;
        uchar           b;
        b = 0;
        for ( a = 0; a < inst.length; a++ )
        {
            b = b + sample[a];
            sample[a] = b;
        }