Check: this looks like a bug in the ModpathReader::ReadData method

[scharlton2]

I think the backwards variable should be a reference:

https://github.com/MODFLOW-USGS/modelviewer-mf6/blob/5cc4c29bd2a0c234abe99f6fdb5cf55a03ea2c83/mv/ModpathReader.cpp#L20