There are some group codes (i.e. "62") which are interpreted as
dxfDataType::SHORT. That's right because the dxf-specification defines
"16 bit integer" as the type for the corresponding value.
But readerBase::readGroup() calls readValue(std::ifstream&, unsigned
short). I changed readValue(std::ifstream&, unsigned short) to
readValue(std::ifstream&, short). I found no group code at the dxf-specs
which needs a "16 bit unsigned integer" value. So the
readValue(std::ifstream&, unsigned short) function is obsolete - right?
