Update Makefile

Makefile

@@ -36,7 +36,7 @@ help:
 clean:
 	-rm -rf $(BUILDDIR)/*
 
-html: _themes
+html: themes
 	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
 	@echo
 	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html."
@@ -61,7 +61,7 @@ json:
 	@echo
 	@echo "Build finished; now you can process the JSON files."
 
-htmlhelp: _themes
+htmlhelp: themes
 	$(SPHINXBUILD) -b htmlhelp $(ALLSPHINXOPTS) $(BUILDDIR)/htmlhelp
 	@echo
 	@echo "Build finished; now you can run HTML Help Workshop with the" \
@@ -130,6 +130,6 @@ doctest:
 	      "results in $(BUILDDIR)/doctest/output.txt."
 
 _themes:
-	git submodule update --init
+	git submodule update --init --recursive