Respect tab order for prev/next buttons (#1051)

This doesn't affect the display, it looks like before,
but now the tab is order is correct.

Author: stsewd

sphinx_rtd_theme/breadcrumbs.html

@@ -72,12 +72,12 @@
 
   {% if (theme_prev_next_buttons_location == 'top' or theme_prev_next_buttons_location == 'both') and (next or prev) %}
   <div class="rst-breadcrumbs-buttons" role="navigation" aria-label="breadcrumb navigation">
-      {% if next %}
-        <a href="{{ next.link|e }}" class="btn btn-neutral float-right" title="{{ next.title|striptags|e }}" accesskey="n">{{ _('Next') }} <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
-      {% endif %}
       {% if prev %}
         <a href="{{ prev.link|e }}" class="btn btn-neutral float-left" title="{{ prev.title|striptags|e }}" accesskey="p"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> {{ _('Previous') }}</a>
       {% endif %}
+      {% if next %}
+        <a href="{{ next.link|e }}" class="btn btn-neutral float-right" title="{{ next.title|striptags|e }}" accesskey="n">{{ _('Next') }} <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
+      {% endif %}
   </div>
   {% endif %}
   <hr/>

sphinx_rtd_theme/footer.html

@@ -1,12 +1,12 @@
 <footer>
   {%- if (theme_prev_next_buttons_location == 'bottom' or theme_prev_next_buttons_location == 'both') and (next or prev) %}
     <div class="rst-footer-buttons" role="navigation" aria-label="footer navigation">
-      {%- if next %}
-        <a href="{{ next.link|e }}" class="btn btn-neutral float-right" title="{{ next.title|striptags|e }}" accesskey="n" rel="next">{{ _('Next') }} <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
-      {%- endif %}
       {%- if prev %}
         <a href="{{ prev.link|e }}" class="btn btn-neutral float-left" title="{{ prev.title|striptags|e }}" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> {{ _('Previous') }}</a>
       {%- endif %}
+      {%- if next %}
+        <a href="{{ next.link|e }}" class="btn btn-neutral float-right" title="{{ next.title|striptags|e }}" accesskey="n" rel="next">{{ _('Next') }} <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a>
+      {%- endif %}
     </div>
   {%- endif %}