golangci-lint configuration file

golangci-lint can run all the currently enabled linters, and as far as I
can tell, does it in under 5 seconds as opposed to over 180 seconds
(compare `time make cilint` and `time make lint`).

Some of the linters that are listed in the "enabled" section but
commented out looked like a good idea to me, and fairly low hanging
fruit to fix, but they are not passing at the moment.

All the linters covered in the current Makefile are run.

TODO:
- replace lint target in Makefile with golangci-lint
- remove .github/workflow/errcheck.yml

Makefile

@@ -86,6 +86,9 @@ install:
 	@echo "${APP} installed into ${INSTALLPATH}"
 
 ## lint: runs a number of code quality checks against the source code
+cilint:
+	golangci-lint run
+
 lint:
 	@echo "\033[35mhttps://github.com/kisielk/errcheck\033[0m"
 	errcheck ./app