hooks and docs to enforce a maximum number of cycles

[turadg]

Thanks for this plugin. It helped us detect a bunch of cycles. :)

As we knock out cycles, we want to ensure new ones aren't introduced. So we need to error, but can't go full failOnError until we get down to zero.

This PR adds hooks for start and end of the cycle detection, which can be used to set a max cycles policy. It also documents how in the README.

---

This change is 

[aackerman]

I'm not seeing a strong need for onStartDetecting aside from having symmetry to onEndDetecting even in your example, the variable is initialized before the module and in onStartDetecting.

If you agree I would say go ahead and remove it. Even if you don't, I would like the methods renamed to onStart and onEnd before merging these changes.

[turadg]

I'm not seeing a strong need for onStartDetecting aside from having symmetry to onEndDetecting

Is that not reason enough? :)

even in your example, the variable is initialized before the module and in onStartDetecting.

I was thinking it needs to be reset on each start of detection. I use webpack-dev-server and I figured the module level would only run once.

I would like the methods renamed to onStart and onEnd before merging these changes.

Will do.

[turadg]

I just rebased off upstream/master

[turadg]

@aackerman, are there any other blockers to merging?

[aackerman]

Published in version 4.4.0