Fix html entities: support \<entity>{} and prevent partial replacements

org/testdata/inline.html

@@ -69,4 +69,11 @@ not emphasized/</li>
 <p><code class="verbatim">#+MACROs</code>: <p><h1>yolo</h1></p>
 </p>
 </li>
+<li>
+<p>org entities</p>
+<ul>
+<li><code class="verbatim">\pi</code> &amp; <code class="verbatim">\pi{}</code> =&gt; π &amp; π</li>
+<li><code class="verbatim">\angle{}</code> &amp; <code class="verbatim">\angle</code> &amp; <code class="verbatim">\ang</code> <code class="verbatim">&gt;</code> ∠ ∠ ∠</li>
+</ul>
+</li>
 </ul>

org/testdata/inline.org

@@ -51,3 +51,6 @@
   - [[example_interpolate_h:tag value with specical chars % : &]] (w/o tag [[example_interpolate_h]])
 - =#+MACROs=: {{{headline(yolo)}}}
   #+MACRO: headline @@html:<h1>$1</h1>@@
+- org entities
+  - =\pi= & =\pi{}= => \pi & \pi{}
+  - =\angle{}= & =\angle= & =\ang= =>= \angle{} \angle \ang

org/testdata/inline.pretty_org

@@ -51,3 +51,6 @@
   - [[example_interpolate_h:tag value with specical chars % : &]] (w/o tag [[example_interpolate_h]])
 - =#+MACROs=: {{{headline(yolo)}}}
   #+MACRO: headline @@html:<h1>$1</h1>@@
+- org entities
+  - =\pi= & =\pi{}= => \pi & \pi{}
+  - =\angle{}= & =\angle= & =\ang= =>= \angle{} \angle \ang