The cnetedit application has been refactored to be callable; Makefile…

… tests have been removed and replaced by gtests (DOI-USGS#5348)

* The cnetedit application has been refactored to be callable; Makefile tests have been migrated to gtest format. Addresses DOI-USGS#5346.

* Removed extraneous variables from FunctionalTestsCnetedit.cpp. Addresses DOI-USGS#5346.

* Updated gtests; replace cubes with labels. Addresses DOI-USGS#5346.

* Per review cleaned up sloppy spacing; made global variables static in cnetedit.cpp to avoid issues when linking libisis. Addresses DOI-USGS#5346.

CHANGELOG.md

@@ -36,7 +36,8 @@ release.
 ## [Unreleased]
 
 ### Changed
-- Cnetedit has been refactored to be callable; old Makefile tests have been removed and replaced by gtests. Issue: [#5322](https://github.com/USGS-Astrogeology/ISIS3/issues/5322), 
+- Cnetedit has been refactored to be callable; old Makefile tests have been removed and replaced by gtests. Issue: [#5346](https://github.com/USGS-Astrogeology/ISIS3/issues/5346), 
+- Cnetdiff has been refactored to be callable; old Makefile tests have been removed and replaced by gtests. Issue: [#5322](https://github.com/USGS-Astrogeology/ISIS3/issues/5322), 
 - Removed the `.py` extention from the _isisdataeval_ tool `isisdata_mockup` for consistency and install it in $ISISROOT/bin; added the `--tojson` and `--hasher` option to _isisdata_mockup_ tool improve utility; updated the tool `README.md` documentation to reflect this change, removed help output and trimmed example results;  fixed paths to test data in `make_isisdata_mockup.sh`. [#5163](https://github.com/DOI-USGS/ISIS3/pull/5163)
 - Significantly refactored FASTGEOM processing in <i>findfeatures</i> to accommodate stability and functionality. The scope of the algorithm was taken out of the ImageSource class and isolated to support this feature. [#4772](https://github.com/DOI-USGS/ISIS3/issues/4772)
 - Report better information regarding the behavior of <i>findfeatures</i>, FASTGEOM algorithms, and creation of the output network. [#4772](https://github.com/DOI-USGS/ISIS3/issues/4772)