feature: expose node information to node related callbacks

[LonelyPrincess]

This PR exposes the node data to the callback methods for all the node-related events. This will give developers access to all of the node's information (including its coordinates). Therefore, this should solve #306.

The event handlers affected by this change are:

• onClickNode
• onDoubleClickNode
• onRightClickNode
• onMouseOverNode
• onMouseOutNode

To obtain the node's information, users can make use of a new parameter on the callback functions, like in the example below:

const onMouseOverNode = function(nodeId, node) {
  window.alert(`Mouse over node ${nodeId} in position (${node.x}, ${node.y})`);
};

The nodeId is still returned first to keep compatibility with previous versions of the library. In the future we may want to delete this property and just return the node itself (as the id can be read from the node object directly).

---

Task list:

💻 Development

• Send node param from the Graph component's node event handlers to the user defined ones located in the props object.

📝 Documentation

• Update node callback methods usage example in README file.
• Update node callback methods usage example in DOCUMENTATION file.
• Update node callback methods usage example in Graph component docs.

🐳 Project settings

• Increase version number to 2.6.0.

[danielcaldas]

Nicelly done 👏 I didn't tought of adding the node parameters to all the callbacks in the API, but looking at it done, it made me thought that it's actually better to have all the callback APIs aligned. Thanks! I'll leave this one for @terahn to merge

[danielcaldas]

Sorry got to carried away by the changes! I actually want to request changes before approving 😄 Please see my notes on some of the changes that we need to drop before merging. Cheers!

[LonelyPrincess]

Thanks for the feedback! 😃

I didn't tought of adding the node parameters to all the callbacks in the API, but looking at it done, it made me thought that it's actually better to have all the callback APIs aligned.

Yeah, that's what I thought too! It's better if we provide the same information in all callbacks, rather than having this added in just one. It's very possible that users request this data in different scenarios after all: even if the original issue asked for onMouseOverNode, someone else may have a similar use case but when they click on the node, for example.

I actually want to request changes before approving 😄 Please see my notes on some of the changes that we need to drop before merging.

I've just dropped the commits that updated the README, DOCUMENTATION and package.json files, just as you requested. Hope it's okay now! 👍🏻