Put short footnotes on one line again

Unlike before, this doesn't force the number to be on the same line as
strongly, that's fine.

So short footnotes look like

-------------
[1] Some text
-------------

Longer footnotes may look like

--------------
[2]

Some more text
--------------

doc_src/python_docs_theme/static/pydoctheme.css

@@ -538,6 +538,15 @@ div.bodywrapper {
     margin-left: 230px;
 }
 
+aside.footnote > .label {
+    display: inline;
+}
+
+aside.footnote > p {
+    display: inline-block;
+    line-height: 1.5em;
+}
+
 /* On screens that are less than 700px wide remove anything non-essential
    - the sidebar, the gradient background, ... */
 @media screen and (max-width: 700px) {