Enable indentation / newlines in MathML writer

luamml-tex.lua

@@ -50,7 +50,7 @@ local function save_result(xml, display)
   local filename = token.scan_argument()
   if filename ~= '' then
     assert(io.open(filename, 'w'))
-      :write(write_xml(make_root({[0] = 'mrow', xml}, display and 0 or 2)) .. '\n')
+      :write(write_xml(make_root({[0] = 'mrow', xml}, display and 0 or 2), true):sub(2) .. '\n')
       :close()
   end
   if tex.count.tracingmathml > 1 then

luamml-xmlwriter.lua

@@ -46,5 +46,5 @@ end
 
 return function(element, indent, version)
   return (version == '11' and '<?xml version="1.1"?>' or '') ..
-    write_elem(element, indent and '' or nil)
+    write_elem(element, indent and '\n' or nil)
 end