fix(openLinksInNewWindow): hash links are not affected by the option

Closes #457

dist/showdown.js

@@ -2598,7 +2598,9 @@ showdown.subParser('anchors', function (text, options, globals) {
       result += ' title="' + title + '"';
     }
 
-    if (options.openLinksInNewWindow) {
+    // optionLinksInNewWindow only applies
+    // to external links. Hash links (#) open in same page
+    if (options.openLinksInNewWindow && !/^#/.test(url)) {
       // escaped _
       result += ' target="¨E95Eblank"';
     }

src/subParsers/anchors.js

@@ -44,7 +44,9 @@ showdown.subParser('anchors', function (text, options, globals) {
       result += ' title="' + title + '"';
     }
 
-    if (options.openLinksInNewWindow) {
+    // optionLinksInNewWindow only applies
+    // to external links. Hash links (#) open in same page
+    if (options.openLinksInNewWindow && !/^#/.test(url)) {
       // escaped _
       result += ' target="¨E95Eblank"';
     }

test/features/openLinksInNewWindow/hash-links-open-in-same-page.html

@@ -0,0 +1 @@
+<p>this link is in the <a href="#same-page">same page</a></p>

test/features/openLinksInNewWindow/hash-links-open-in-same-page.md

@@ -0,0 +1 @@
+this link is in the [same page](#same-page)