Use Sublime Text to Diff two files in the same folder for SWMM 5 C Code

Sublime Text is nice but not a free Text Editor for large files.  However, it does have a limited file difference capability – here is how you can use Sublime Text to Diff two files in the same folder for SWMM 5 C Code.  You can also use this to compare dozens of files in Sublime - which is needed for a program such as SWM 5 which has been continuously updated from 2003 to 2017 with at least 35? major version.  This makes it easy for example to compare the groundwater or rdii code between 2005 / 2012 and 2017, for example.