Cleans NEMA data collected for a GPR unit.

gprfix was developed to "clean" NEMA data collected for a GPR unit.

The executable takes no arguments. It simply:

1. creates a subfolder named "Clean_DZGs"
2. looks for all "DZG" files in the current folder
3. loads each file one line at a time
4. retains any line that starts with "GSSIS" or "GPGGA"
5. removes duplicate "GSSIS" lines between "GPGGA" lines
6. creates and writes a revised file with the same name into the "Clean_DZGs" folder

To do in the future:

1. generalize the pattern it looks for
2. allow files with other extensions to be loaded
3. better error checking