Add a couple integration tests for ext links vs. <dl>.

tests/tokenizer/integration.mwtest

@@ -58,3 +58,17 @@ name:   wildcard_redux
 label:  an even wilder assortment of various things
 input:  "{{a|b|{{c|[[d]]{{{e}}}}}}}[[f|{{{g}}}<!--h-->]]{{i|j=&nbsp;}}"
 output: [TemplateOpen(), Text(text="a"), TemplateParamSeparator(), Text(text="b"), TemplateParamSeparator(), TemplateOpen(), Text(text="c"), TemplateParamSeparator(), WikilinkOpen(), Text(text="d"), WikilinkClose(), ArgumentOpen(), Text(text="e"), ArgumentClose(), TemplateClose(), TemplateClose(), WikilinkOpen(), Text(text="f"), WikilinkSeparator(), ArgumentOpen(), Text(text="g"), ArgumentClose(), CommentStart(), Text(text="h"), CommentEnd(), WikilinkClose(), TemplateOpen(), Text(text="i"), TemplateParamSeparator(), Text(text="j"), TemplateParamEquals(), HTMLEntityStart(), Text(text="nbsp"), HTMLEntityEnd(), TemplateClose()]
+
+---
+
+name:   link_inside_dl
+label:  an external link inside a def list, such that the external link is parsed
+input:  ";;;mailto:example"
+output: [TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), ExternalLinkOpen(brackets=False), Text(text="mailto:example"), ExternalLinkClose()]
+
+---
+
+name:   link_inside_dl_2
+label:  an external link inside a def list, such that the external link is not parsed
+input:  ";;;malito:example"
+output: [TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), TagOpenOpen(wiki_markup=";"), Text(text="dt"), TagCloseSelfclose(), Text(text="malito"), TagOpenOpen(wiki_markup=":"), Text(text="dd"), TagCloseSelfclose(), Text(text="example")]