Prepare a breaking build

[kanongil]

Contains two breaking changes that removes functionality (#65 & #73), and two breaking changes for maintenance (#74 & #75).

Note that when I removed promise support from emit(), I took care to preserve the behaviour that a handler throw will not stop the other handlers from being called. This is different from how node events work, where a throw immediately falls up the the caller.

Besides the breaking changes, I also took the opportunity to do some cleaning, which can be seen through the remaining commits. For instance I completely removed exports.decorate() which was poorly implemented, not documented, and not used in any hapi projects.

The only outstanding issue before this is ready to be published, is updating any dependencies that are going to have a breaking release for hapijs/hapi#4279. This is pending that they are actually published.

If anyone is up for it, there are some undocumented (and not in ts.d) APIs that would be nice to finally include: The ones I have found are:

1. exports.validate() (used in hapi, catbox & beam)
2. the options argument of new Podium() and podium.registerEvent()
3. podium.once() called without a listener (which then returns a promise).
4. the podium.few() method.

Additionally, I feel that it would be nice to add a podium.off() method that aliases podium.removeListener().

Let me know if I should break up the first two commits into separate PRs for easier review (but where should it be merged to?).

[devinivy]

The work in here looks great. I have peeled-off a v5 branch and will be incorporating this into there alongside some of the other changes that have been documented through issues (primarily thinking of gauge() and off()). Thanks!

[devinivy]

👍 I am into some well-placed jsdoc type annotations.