Upgraded from ANTLR 3.3 to 3.5.2 so that preon works with Java 8.

Before the change, preon was complaining of a NullPointerException in
CompositeGrammer.getIndirectDelegates.  Please see
antlr/antlr3#151 for more information on this
bug that has been resolved in ANTLR 3.5.2

preon-el/pom.xml

@@ -19,7 +19,7 @@
     <dependency>
       <groupId>org.antlr</groupId>
       <artifactId>antlr-runtime</artifactId>
-      <version>3.3</version>
+      <version>3.5.2</version>
     </dependency>
     <dependency>
       <groupId>junit</groupId>
@@ -66,7 +66,7 @@
       <plugin>
         <groupId>org.antlr</groupId>
         <artifactId>antlr3-maven-plugin</artifactId>
-        <version>3.3</version>
+        <version>3.5.2</version>
         <executions>
             <execution>
                 <phase>generate-sources</phase>