Excplicitly check that urls start with http:// or https://

This is slightly better than macthing only "http"

Found by ZeroPath

Reported by: Joshua Rogers <joshua@joshua.hu>

Signed-off-by: Selva Nair <selva.nair@gmail.com>

misc.c

@@ -745,7 +745,7 @@ md_final(md_ctx *ctx, BYTE *md)
 BOOL
 open_url(const wchar_t *url)
 {
-    if (!url || !wcsbegins(url, L"http"))
+    if (!url || (!wcsbegins(url, L"http://") && !wcsbegins(url, L"https://")))
     {
         return false;
     }