Add basic Conan support

[Croydon]

This adds basic Conan support.

Packages can be build with

conan create . entt/<version-number>@skypjack/stable

Packages can be tested with

conan create . entt/<version-number>@skypjack/stable -tf conan/test_package

(the parameter tf stands for test_package)

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I will create a separate pull request for adding CI building/testing/publishing later.

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Cross-referencing: conan-io/wishlist#166

[coveralls]

Coverage remained the same at 100.0% when pulling a2cb6f8 on Croydon:croydon/conan into 2a4e098 on skypjack:master.

[indianakernick]

There’s already a script that publishes to Homebrew. You could quite easily add a new script for publishing to Conan. The script is run automatically by Travis.

[Croydon]

@Kerndog73 Yes, of course, but divide&conquer pull requests is also a good thing :)

At Bincrafters we maintain templates for Conan and I will re-use them (https://github.com/bincrafters/conan-templates & https://github.com/bincrafters/conan-templates-upstream)

[skypjack]

Just a side question: is it possible to turn conan dir to .conan as it happened for uvw?

[Croydon]

Just a side question: is it possible to turn conan dir to .conan as it happened for uvw?

I can rename it if you want. It's just more common for us to use a conan directory instead of a .conan one.

[skypjack]

Stick with the convention. Just a matter of tastes. Not a problem. 👍

[skypjack]

@Croydon may I ask you to help me to port the conan stuff to GH actions?
I'm having troubles and I don't know how to solve it.
Branch wip contains the current configuration.

[skypjack]

Nevermind. It works. 👍