Remove "get"/"set" prefixes from API methods

We sometimes use a "get"/"set" prefix (SearchResult.getHits(), PropertyBindingContext.setBridge(...), ...), but most of the time we don't (Search.session(...), IndexManager.descriptor(), various DSLs that don't use "set", ...).

I think we should be consistent and not use the prefixes anywhere, for the sake of consistency and brevity. JavaBeans or JPA entity conventions don't apply here, as we're not talking about JavaBeans nor JPA entities.

Old methods with the prefixes should be kept as deprecated for now, of course. There shouldn't be many of them.