Test Lua filter converting display math to inline math

test/lua/math.lua

@@ -0,0 +1,10 @@
+return {
+  {
+    Math = function (elem)
+      if elem.mathtype == "DisplayMath" then
+        elem.mathtype = "InlineMath"
+      end
+      return elem
+    end,
+  }
+}