Update pixi.js to version 5.2.1 🚀

[giabao]

Description

• Update pixi.js 5.2.0
• Remove eventemitter3 peer & dev dependency
  We now use (in eventemitter3-patch.ts) PIXI.utils.EventEmitter directly
  pixi 5.2.0 also don't list eventemitter3 as a dependency
• update mocha 7.0.0 & sinon 8.0.2

Related Issue

#121

Motivation and Context

We should support pixi 5.x, maybe through a separated branch.

How Has This Been Tested?

I have verify the changes by running the following npm scripts:

yarn clean-up
yarn compile:src
yarn compile:test
yarn compile:example
yarn tslint
yarn build
yarn test
yarn start

and then browse the url (output of yarn start command) to manually verify in browser.

Types of changes

• Updated docs / Refactor code / Added a tests case (non-breaking change)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[tiagoschenkel]

@giabao, many thanks for your contribution! I'm making some general updates on all packages, will release this new version when possible.