When input and output .pto differ in base path, image paths not correctly preserved

[Bob-O-Rama]

Take for instance:

/build/opencv/cvfind/cvfind --detect akaze --pattern lrtb --rowsize 10 --overlap 30 --log --alignlog --savediag neighbors --sprawlratio 0.97 --loopanalysis --debug -o **series_f_base_sr097**_noloop.pto **../../cvfind_test_Images/series_f/series_f_base.pto**

The input images referenced by ../../cvfind_test_Images/series_f/series_f_base.pto are unqualified and in the same path as the .pto file. When writing the output, the file names are unmodified and broken relative to the output PTO and the PTO errors out when read by Hugin or subsequent cvfind usage.

cvfind should generate PTO files which work without modification, e.g. hugin output.pto after cvfind completes from the command line.