ObjectIndex: eliminate long lines
ObjectIndex: eliminate warnings
Remove duplicate blank lines
ObjectIndex: add missing section header
ObjectIndex: add a log field, for logging things

A following commit will add a new feature to the ObjectIndex which might
encounter problems, so it will be nice to have access to an (optional)
logging mechanism for reporting them.
Register log mechanism with ObjectIndex instances
ObjectIndex: allow lazy registration of objects
AbstractSingletonService: register instances lazily

To be more precise, the objects were previously registered lazily upon
the first call to SingletonService#getInstances(). Unfortunately,
calling ObjectService#get or ObjectService#getAll before that failed to
return the singleton instances, because they had not yet even been
instantiated. To address this problem, we now register them using the
ObjectIndex's newly minted addLater feature, which lets us define a
FutureTask to create and register them as soon as they are needed.