modules.{dot,summary} anomalies

[Alan Bateman]

Mandy,

I notice duplicate dependencies printing to modules.summary and 
modules.dot when grouping modules. It looks like printModulesSummary and 
printModulesDot need to first aggregate the dependencies by group (with 
hard dependency having priority over optional and dynamic 
dependencies).  Do you have time to fix this or do you want me to fix it?

In passing it also looks like Module.Dependency has issues in that it's 
hashCode/equals/compareTo don't look right. An easy solution would be to 
make it immutable and to fix up the issues in the places that use this 
class. What do you think?

-Alan.