Do not assume \markdownInput input comes from \markdownOptionOutputDir

Closes #57

Author: Witiko

markdown.dtx

@@ -16031,7 +16031,10 @@ local convert = md.new(\markdownLuaOptions)
           |markdownInfo{The ending token sequence was found}@
           |immediate|closeout|markdownOutputFileStream@
           |endgroup@
-          |markdownInput|markdownOptionInputTempFileName@
+          |markdownInput{@
+            |markdownOptionOutputDir@
+            /|markdownOptionInputTempFileName@
+          }@
           #2}@
       |fi@
 %    \end{macrocode}
@@ -16300,9 +16303,7 @@ local convert = md.new(\markdownLuaOptions)
     |closein|markdownInputFileStream
     |markdownLuaExecute{%
       |markdownPrepare
-      local input = assert(io.open("%
-        |markdownOptionOutputDir
-        /#1", "r"):read("*a"))
+      local input = assert(io.open("#1", "r"):read("*a"))
 %    \end{macrocode}
 % \begin{markdown}
 % Since the Lua converter expects \acro{unix} line endings, normalize the