Solve module compatibility issues, clean up project.

[martinemmert]

This PR fixes the issues regarding the globally used PIXI object and adds support for umd, cjs and esm module types. Sorry for it being that huge. It makes more sense if the code is checked out locally, since a lot of these changes came through prettierjs, moving files and replace yarn by npm.

Since there are no tests, and I am not aware of how I can test this properly with integration tests, you have to trust me when I say it works on my machine 😏 (I updated the examples and added a serve command to ease the use of them locally)

Changes introduced in this PR:

• implemented tsdx as a build tool and set it up for pixi.js packages
• fix linter errors which occurred after installing one
• fix typescript type issues
  • NOTE: the code needs to be refactored with better type guards and updated typings
• reformat code with prettier
• move example assets into the public folder, serve project_dir with npm serve
• remove yarn (npm 7 is way better)
• update tsconfig and set the output to tsnext
• target new browsers without ie11 (might be a bit too strict, and can be revisited especially for the umd export )
• remove auto plugin registration
• add documentation on how to register this plugin
• add documentation on how to import/required this plugin
• add documentation on how to serve the examples locally

Solves, relates or helps with the following issues:
#104 #97 #81 #62 #59 #18 #15

[martinemmert]

@ivanpopelyshev is it possible to upgrade the npm version to version 7 on Travis?
npm 7 does install peer dependencies per default and should fix the current issue since pixi.js is marked as a peer dependency.

[spassvogel]

Does this mean we no longer have to expose PIXI as a global variable? This is great!

[martinemmert]

Does this mean we no longer have to expose PIXI as a global variable? This is great!

Exactly.

Since the author went silent, maybe you can try out my PR and post your findings here.

[spassvogel]

Okay I don't mind to do that. So once I've pulled your branch I gotta do npm build and npm link and then npm link pixi-tilemap from my project folder to test it in my project locally, right?

[martinemmert]

Yes, that's how I use it currently. Make sure you have npm 7 installed 👍

[ShukantPal]

This should be handled by #111 , #110 , #95. Working on a leaner and better documented pixi-tilemap for v3.