enable running jython from a directory with an exclamation mark in it…

…'s name

due to jdk limitations this is only possible for
 + jdk 1.6 and higher
 + directory names not ending with an exclamation mark

due to the special treatment of exclamation marks in enabledelayedexpansion, this is currently not possible for jython.bat on windows

installer autotests now use an exclamation mark if possible

src/org/python/core/PySystemState.java

@@ -889,7 +889,7 @@ private static String getJarFileName() {
         if (url != null) {
             try {
                 String urlString = URLDecoder.decode(url.toString());
-                int jarSeparatorIndex = urlString.indexOf(JAR_SEPARATOR);
+                int jarSeparatorIndex = urlString.lastIndexOf(JAR_SEPARATOR);
                 if (urlString.startsWith(JAR_URL_PREFIX) && jarSeparatorIndex > 0) {
                     jarFileName = urlString.substring(JAR_URL_PREFIX.length(), jarSeparatorIndex);
                 }