Add id field to each execution

[cowboyd]

It's nice when debugging to see how forks relate to each other both inside and outside of code. To do this you need a consistent way to identify a fork.

This adds an id field which is allocated from a static id sequence inside the Fork constructor. I've opted to install the class properties syntax since it is so pervasive and cleaner than using a module variable.

I also like the idea of being able to read it as a property from the Fork constructor rather than have it completely hidden inside a module variable.

resolves #27

[frontsidejack]

A preview package of this pull request has been released to NPM with the tag add-execution-id.
You can try it out by running the following command:

$ npm install effection@add-execution-id

or by updating your package.json to:

{
  "effection": "add-execution-id"
}

Once the branch associated with this tag is deleted (usually once the PR is merged or closed), it will no longer be available. However, it currently references effection@0.3.3-b4fd9aa which will be available to install forever.

Generated by 🚫 dangerJS against f114768

[frontsidejack]

A preview package of this pull request has been released to NPM with the tag add-execution-id.
You can try it out by running the following command:

$ npm install effection@add-execution-id

or by updating your package.json to:

{
  "effection": "add-execution-id"
}

Once the branch associated with this tag is deleted (usually once the PR is merged or closed), it will no longer be available. However, it currently references effection@0.3.3-c1a4d52 which will be available to install forever.

Generated by 🚫 dangerJS against f081023