Several tweaks to test.py and test runner

These are just some minor quality of life improvements

- Added a "make build-test" alias
- Made test runner a positional arg for test.py since it is almost
  always required. This shortens the command line invocation most of the
  time.
- Added --context to test.py
- Renamed --output in test.py to --stdout, note this still merges
  stderr. Maybe at some point these should be split, but it's not really
  worth it for now.
- Reworked the test_id parsing code a bit.
- Changed the test runner --step to take a range such as -s0,12,2
- Changed tracebd.py --block and --off to take ranges

Makefile

@@ -107,18 +107,18 @@ size: $(OBJ)
 tags:
 	$(CTAGS) --totals --c-types=+p $(shell find -H -name '*.h') $(SRC)
 
-.PHONY: test-runner
-test-runner: override CFLAGS+=--coverage
-test-runner: $(BUILDDIR)runners/test_runner
+.PHONY: test-runner build-test
+test-runner build-test: override CFLAGS+=--coverage
+test-runner build-test: $(BUILDDIR)runners/test_runner
 	rm -f $(TEST_GCDA)
 
 .PHONY: test
 test: test-runner
-	./scripts/test.py --runner=$(BUILDDIR)runners/test_runner $(TESTFLAGS)
+	./scripts/test.py $(BUILDDIR)runners/test_runner $(TESTFLAGS)
 
 .PHONY: test-list
 test-list: test-runner
-	./scripts/test.py --runner=$(BUILDDIR)runners/test_runner $(TESTFLAGS) -l
+	./scripts/test.py $(BUILDDIR)runners/test_runner $(TESTFLAGS) -l
 
 .PHONY: code
 code: $(OBJ)