Use search pattern as delimiter if empty regex is given

Close #78

test/commandline.vader

@@ -105,6 +105,14 @@ Expect:
   ap><pl><e;><:;><;b><an><an><a:><:c><ak>e
   da><ta><;;><ex><ch><an><ge><:;><::><fo> <rm><at
 
+Execute (Use current search pattern as delimiter if empty regular expression is given):
+  /an
+  %EasyAlign*//
+
+Expect:
+  apple;:;;b an  an a::cake
+  data;;exch an ge:;::format
+
 Given javascript (json):
   var jdbc = {
     // JDBC driver for MySQL database: