Cannot compile Velocity with JDK 1.5 due to use of the newly-reserved word "enum"

Currently, Velocity doesn't compile with Java5 because it uses enum in the
following classes:
o.a.v.runtime.parser.Parser
o.a.v.texen.Generator
o.a.v.util.EnumerationIterator

To avoid future issues, I think the source should be changed.

1. 1. Of course, you might have to do something with javacc for Parser...