Add a build_debug target

Makefile.dev

@@ -1,12 +1,16 @@
 # debian/rules would use this Makefile if named so over the default debuild
 # make targets, thus we should avoid naming this file Makefile
 
-build_init:
+build_init: # rerun to copy the files into the builder
 	docker build -t debian-package-builder .
 
 build_run: # builds in a docker container and output to the ./out/ dir
 	mkdir -p $$(pwd)/out
 	docker run --rm -v $$(pwd)/out:/pkg debian-package-builder
 
+build_debug: # run a bash into the container for debugging
+	mkdir -p $$(pwd)/out
+	docker run -it --rm -v $$(pwd)/out:/pkg debian-package-builder /bin/bash
+
 build_clean:
 	docker rm debian-package-builder