MAINT: rm reference docs for doctests; html-only

Remove the reference docs for the doctests, because they pick up lots of
failed doctests that are anyway tested in the test suite.

Add html-only target.

Author: matthew-brett

doc/Makefile

@@ -43,12 +43,14 @@ api-stamp:
 	@echo "Build API docs...done."
 	@touch $@
 
-html: api-stamp
+html-only:
 	mkdir -p $(BUILDROOT)/html $(BUILDROOT)/doctrees
 	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDROOT)/html
 	@echo
 	@echo "Build finished. The HTML pages are in $(BUILDROOT)/html."
 
+html: api-stamp html-only
+
 pickle:
 	mkdir -p $(BUILDROOT)/pickle $(BUILDROOT)/doctrees
 	$(SPHINXBUILD) -b pickle $(ALLSPHINXOPTS) $(BUILDROOT)/pickle
@@ -87,7 +89,7 @@ linkcheck:
 	@echo "Link check complete; look for any errors in the above output " \
 	      "or in $(BUILDROOT)/linkcheck/output.txt."
 
-doctest:
+doctest: api-clean
 	$(SPHINXBUILD) -b doctest $(ALLSPHINXOPTS) $(BUILDROOT)/doctest
 	@echo "Testing of doctests in the sources finished, look at the " \
 	      "results in _build/doctest/output.txt."