Add targets for docker stuff, remove bogus target

lcthw-remnants-2/Makefile

@@ -4,15 +4,12 @@ LDLIBS = -ldl
 
 EXERCISES := $(shell ./list-exercises)
 
-all: $(EXERCISES) libex29.so
+all: $(EXERCISES)
 
 ex19: object.o
 
 ex22_main: ex22.o
 
-libex29.so: libex29.o
-	$(CC) -shared -o $@ $<
-
 clean:
 	shopt -s nullglob ; \
 	$(RM) $(EXERCISES) *.o *.a
@@ -22,3 +19,11 @@ test:
 
 exercises:
 	@echo $(EXERCISES)
+
+.PHONY: docker-image
+docker-image:
+	docker build -t meatballhat/lcthw:latest .
+
+.PHONY: docker-run
+docker-run:
+	docker run -it -v $(PWD):/app meatballhat/lcthw:latest bash -l