[photran-dev] @Override annotations

[Jeffrey Overbey <overbey2@xxxxxxxxxxxx>]

I modified the compilers settings for all of the Photran projects except 
Intel's and core.vpg to require @Override annotations.  (I actually 
forgot that we weren't explicitly requiring them.)

I will add this to core.vpg as well after I fix the AST generator, since 
it's missing them in a couple of places.

Note that we're compiling with Java 1.5 settings, so @Override 
annotations are required on methods overridden from a superclass but are 
*not allowed* on methods overridden from interfaces (that was added in 
Java 1.6).

Jeff