Add Type Safety to "chainId"

[rogerluan]

Overview

This PR adds an enum, EthereumChain, that is a type-safe wrapper for the chainId, as described in EIP155.

Detailed

This PR also makes the chainId parameters mandatory, instead of providing a default value (which was originally 0), review the documentation and update the README file accordingly.

Note

Pardon the extra verbosity on the enum declaration, but in order to implement the .custom case with an associated value, the enum could not inherit directly from Int as those don't allow values to be associated with them. So I had to implement the enum, manually conforming to RawRepresentable.

I'm not too fussed if you guys decide to drop support for the lesser known networks in order to keep the API clean, I just threw in all the chainIds I found browsing Stack Overflow 😇

Resolves https://github.com/Boilertalk/Web3.swift/issues/53

[rogerluan]

@pixelmatrix @Ybrin, I just implemented the requested changes 👍

[pixelmatrix]

Looks good to me. Have you looked into the failing tests?

[rogerluan]

I'll take a look at those issues soon, sorry for the wait guys.

[koraykoska]

@rogerluan Have you had a chance to look into these issues yet?

[rogerluan]

@Ybrin Sorry, not yet. I definitely didn't forget it! 😅 If anyone else wanna address the changes, by all means! Otherwise I'll be checking this later 👍 Sorry for the wait 😞

[rogerluan]

I apologize for the really long wait, but I finally took some time to look into the failing tests 😅 Let me know if there are any other pending issues here @Ybrin @pixelmatrix ! 😃

[codecov[bot]]

Codecov Report

Merging #62 into master will increase coverage by 0.23%. The diff coverage is 55.26%.

@@            Coverage Diff             @@
##           master      #62      +/-   ##
==========================================
+ Coverage   75.14%   75.38%   +0.23%     
==========================================
  Files          64       64              
  Lines        4152     4164      +12     
==========================================
+ Hits         3120     3139      +19     
+ Misses       1032     1025       -7

Impacted Files	Coverage Δ
...Classes/Core/Transaction/EthereumTransaction.swift	73.46% <55.26%> (+5.53%)	:arrow_up:

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[koraykoska]

@rogerluan Thanks. Looks good now. Gonna merge it soon for the next version jump.