Added support for attr_lists on definition list terms.

Like headers (h1-6) dt's can only be on one line, so we need to use
the header regex on dt's. This was implemented after considering a recent
[discussion](http://six.pairlist.net/pipermail/markdown-discuss/2013-July/002859.html)
on the markdown mailing list. Prior to that discussion, I never considered
that it was impossable to set block level attrs on dt's. Now it is.

markdown/extensions/attr_list.py

@@ -80,8 +80,8 @@ def run(self, doc):
             if isBlockLevel(elem.tag):
                 # Block level: check for attrs on last line of text
                 RE = self.BLOCK_RE
-                if isheader(elem):
-                    # header: check for attrs at end of line
+                if isheader(elem) or elem.tag == 'dt':
+                    # header or def-term: check for attrs at end of line
                     RE = self.HEADER_RE
                 if len(elem) and elem.tag == 'li':
                     # special case list items. children may include a ul or ol.

tests/extensions/attr_list.html

@@ -48,4 +48,13 @@ <h1>And ordered lists <em class="inline">too</em></h1>
 </ol>
 </li>
 <li>Item5</li>
-</ol>
+</ol>
+<h1 class="block">Definition <em>lists</em></h1>
+<dl>
+<dt class="term">DT1</dt>
+<dt class="term">DT2</dt>
+<dd class="def">Some dd</dd>
+<dd><em class="inline">dd</em></dd>
+<dt><em class="inline">DT3</em></dt>
+<dd>Some dd</dd>
+</dl>

tests/extensions/attr_list.txt

@@ -65,3 +65,14 @@ Also a codespan: `{: .someclass}`{: .foo}.
     1. Item4-1
 5. Item5
 
+# Definition *lists* {.block}
+
+DT1 {.term}
+DT2 {.term}
+:   Some dd
+    {.def}
+:   *dd*{.inline}
+
+*DT3*{.inline}
+:   Some dd
+

tests/extensions/test.cfg

@@ -1,5 +1,5 @@
 [attr_list]
-extensions=attr_list
+extensions=attr_list,def_list
 
 [codehilite]
 extensions=codehilite