Display an icon on non-win32 machines

[cbosdo]

On Linux platforms, the icon needs to be a PNG file. On MacOS too
according to this page:

https://developer.apple.com/design/human-interface-guidelines/macos/icons-and-images/app-icon/

Notes:

• As I don't have a macos, I couldn't test that it works there
• I couldn't find a way to change the "Electron" into "Oni" in the application name

[cbosdo]

looks like the builds are broken... but not due to this PR

[CrossR]

Sorry for the delay!

Which OS' should this fix it for? I know Windows is obviously fine, but from my other machines Ubuntu and macOS do have icons in the docks/alt-tab menus etc. The only other linux box I have is an Arch one, but since that has a tiling WM I never really seen any icons anyways.

[cbosdo]

@CrossR At least here on openSUSE I had a blank icon using the .ico file.

[CrossR]

Given it a quick test and works fine for me!

Cheers for fixing this!

[CrossR]

I've not got access to AppVeyor at the moment for whatever reason, so I'll need @Akin909 or @bryphe to restart the build (or I think @bryphe can maybe ignore the checks?), since you are right its nothing to do with your changes.

[keforbes]

@bryphe, what would it take to add me and @CrossR to the list of users allowed to restart AppVeyor builds? I've noticed the same thing, I don't have permission.

[bryphe]

@bryphe, what would it take to add me and @CrossR to the list of users allowed to restart AppVeyor builds? I've noticed the same thing, I don't have permission.

Sorry about that guys! I meant to add all the collaborators to it (its lame that AppVeyor doesn't sync up permissions). There's two things I need to add:

1. You need to log-in at least once with your GitHub account on https://ci.appveyor.com to get added to the system.
   
2. Once you're in the system, I can add you to the team - I just need the e-mail associated with your GitHub account.

[bryphe]

Update - actually, was able to add you both @CrossR and @keforbes - sorry it wasn't working before! You should have permission now to restart builds. Let me know if that's not the case.

[codecov]

Codecov Report

Merging #2363 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2363   +/-   ##
=======================================
  Coverage   38.07%   38.07%           
=======================================
  Files         300      300           
  Lines       12508    12508           
  Branches     1645     1645           
=======================================
  Hits         4763     4763           
  Misses       7491     7491           
  Partials      254      254

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[bryphe]

Merging this in now @cbosdo - thank you for the contribution! 💯 Sorry about the build issues.