Upgrade Jasper to get sensible compilation errors

The current Jasper tag used in 6.1.5:
SJSAS-9_1-B50G-BETA3-27_June_2007

gives obscure NPE exception that hides the real messages.

The problem has been encountered in other places.
http://forums.java.net/jive/message.jspa?messageID=227424

I can reproduce the error by having:
include.jsp:
<%
foo // deliberately wrong
%>

foo.jsp:
Hello world

web.xml
<jsp-property-group>
<url-pattern>*.jsp</url-pattern>
<page-encoding>UTF-8</page-encoding>
<include-prelude>/include.jsp</include-prelude>
</jsp-property-group>
</jsp-config>

Note that this is not the same as a previous issue (Jetty < 6.1.5) where a similar obscure ClassCastException was hiding the real error.