private void scanOffsets () throws IOException {
        files = source.readShort();
        offsets = new int[files];
        ids = new int[files];
        for (int i = 0; i < files; i++) {
            ids[i] = source.readShort();
            offsets[i] = source.readInt();
        }
    }
Read the specified file and return a corresponding CartridgeFile object.

@param source file representing the cartridge
@param savefile save file corresponding to this cartridge
@return a CartridgeFile object corresponding to source
@throws IOException
main/src/main/java/cgeo/geocaching/wherigo/openwig/formats/CartridgeFile.java