Support .It [stuff] Xo

Add a command test since these seem annoying to write in the other
format.

src/Text/Pandoc/Readers/Mdoc.hs

@@ -954,16 +954,15 @@ parseDefinitionList = do
   where
     dlItem = do
       macro "It"
-      dt <- (xoListHead <|> listHead)
+      dt <- (try xoListHead) <|> parseInline
       dd <- mconcat <$> many parseRegularBlock
       return (dt, [dd])
-    -- TODO refactor, maybe extract the bodies of
-    -- lineEnclosure/multilineEnclosure
-    listHead = parseInline
     xoListHead = do
+      before <- option mempty parseInline
       macro "Xo"
       optional eol
-      many1Till parseInlines (emptyMacro "Xc") >>= spacify
+      after <- many1Till parseInlines (emptyMacro "Xc")
+      spacify (before:after)
 
 parseColumnList :: PandocMonad m => MdocParser m Blocks
 parseColumnList = do

test/command/mdoc-Bl-tag.md

@@ -0,0 +1,24 @@
+```
+% pandoc -f mdoc -t native
+.Bl -tag
+.It one
+one
+.It Xo
+two
+.Xc
+two
+.It Em three Xo
+three
+.Xc
+three
+.El
+^D
+[ DefinitionList
+    [ ( [ Str "one" ] , [ [ Para [ Str "one" ] ] ] )
+    , ( [ Str "two" ] , [ [ Para [ Str "two" ] ] ] )
+    , ( [ Emph [ Str "three" ] , Space , Str "three" ]
+      , [ [ Para [ Str "three" ] ] ]
+      )
+    ]
+]
+```