Add typescript support

[GregTheGreek]

Description

This PR focuses on adding TypeScript in an incremental way. Currently allowJs is enabled allowing us to write TypeScript and JavaScript side by side. The configuration is very lenient, and in the future as we make progress on the typescript interfaces we should tighten it up.

It also:

• Changes the build to build using tsc (future change to babel?)
• Changes the tests to run the tsnode/register so typescript is supported
• Adds support for up-to es8 (classes, arrow functions, etc...)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• [ x ] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• [ x ] I have selected the correct base branch.
• [ x ] I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• [ x ] My changes generate no new warnings.
• [ x ] Any dependent changes have been merged and published in downstream modules.
• [ x ] I ran npm run dtslint with success and extended the tests and types if necessary.
• [ x ] I ran npm run test:unit with success.
• [ x ] I ran npm run test:cov and my test cases cover all the lines and branches of the added code.
• [ x ] I ran npm run build and tested dist/web3.min.js in a browser.
• [ x ] I have tested my code on the live network.
• [ x ] I have checked the Deploy Preview and it looks correct.
• [ x ] I have updated the CHANGELOG.md file in the root folder.

[coveralls]

Coverage decreased (-5.9%) to 84.321% when pulling 6f66150 on greg/modernize into b0b135c on 1.x.

[spacesailor24]

Other than the two commented imports, lgtm!

few commits since review

[GregTheGreek]

@spacesailor24 and @ryanio I updated the changelog and addressed a previous comment. Ready for re-review.

new commits

[ryanio]

@GregTheGreek looks good 👍 in the past we have only merged changes to dist/web3.min.js on release (like noted here), what do you think?

[GregTheGreek]

@GregTheGreek looks good in the past we have only merged changes to dist/web3.min.js on release (like noted here), what do you think?

hmm let me look at that, i thought i pulled in the ones from 1.x

[ryanio]

LGTM!