Make EventBus(EventBusBuilder) constructor public.

[trashkalmar]

There are scenarios when it is better to use EventBus as base class. In this case it is impossible to construct custom class which is configured by EventBusBuilder builder.
This PR makes the EventBus(EventBusBuilder) constructor public to support latter case.

[zxw1962]

But this will break the build pattern, if so, user can just new EventBus instance directly, which will make EventBusBuilder.build method less important.

IMO, If there are many choices, there's no choices. What do you say?

[trashkalmar]

Why? User can continue to use pattern and create EventBus instance with builder. However, at this time I'm unable to use EventBus as base class and create descendants configured with the builder.

[william-ferguson-au]

What's the use case for subclassing EventBus?
I would instead argue for making the class final and explicitly disallow subclassing.

[trashkalmar]

Use case is very simple. I'd like to perform some action while registering event handler, i.e. override register/unregister methods in EventBus. Also I'd like to customize EventBus`s behavior with Builder (disable event inheritance in my case).
However, at this time I have to create wrapper and pass register/unregister/post/postSticky calls to wrapped EventBus instance configured with Builder.

[trashkalmar]

@greenrobot so, what do you think?