Add ResourceWatcherEvent

[romainneutron]

Hey,

this PR adds ResourceWatcherEvent providing three events type to interact with the ResourceWatcher itself. It can be very convenient in some case to know when a period has been finished.

For example, if listening to the events in a directory :

• I considering a created / modified file as "hot"
• I wait 10 seconds on a hot file to consider it "cold". If a modification occurs within the 10 seconds, it's still "hot". When it's "cold", I can process it safely (FTP files being written can take long time if the client disconnects then resumes)
• Once the 10 seconds are over, I process it.

With the current implementation, if nothing changes in the directory, there are no events. We have to run ResourceWatcher::start with a time limit , then process files, then re-run etc...

With this PR, this kind of usecase is doable out of the box.

[henrikbjorn]

I like this idea. But i have some comments.

Normally the convention is to have a events class, like Lurker\LurkerEvents that have the constants and then a specific Lurker\Event\ResourceWatcherEvent class.

Instead of going through the getEventDispatcher method i think it would be better to use the property directly.

Looks like the test are not aware of the new events.

[henrikbjorn]

@romainneutron i really want to merge this, but can you have a look at the failing testcase?