WU dump command in AMC13Tool2 doesn't take a directory as part of file name

The "Wu" command dumps registers to a file. With no arguments it tries to write a file to the current directory with a name based on date/time stamp.

An optional second argument specifies a file name, but this name cannot be a full path name. In principle, all these should work:

wu                 # default
wu xyz.txt         # dump to xyz.txt in current dir
wu dumps/xyz.txt   # dump to xyz.txt in dumps under current dir
wu /tmp/xyz.txt    # dump to /tmp/xyz.txt