Version 3 Update

[cmfcmf]

This PR accumulates some breaking changes for version 3, based on #72. I will release version 3 once this PR is merged.

• closes Dealing with Internal error: 500001 #130

[KarelWintersky]

Valid :)

[KarelWintersky]

a little fix:

Must be °F, not an alone F

[cmfcmf]

a little fix:

Must be °F, not an alone F

Good point! Fixed in 6c5eee9

[cmfcmf]

I am considering to drop support for PHP 5.3, 5.4 and 5.5. Here's why:

• PHP <= 5.5 is EOL for almost 3 years
• Many libraries in the ecosystem require PHP 5.6. When I played around with support for PSR-6 Cache (instead of the current custom cache implementation), I quickly ran into issues with cache/array-adapter because it requires at least PHP 5.6.
• I have only briefly looked into PSR-17 and PSR-18 (HTTP Client), but library support for PHP 5 looks similarly bad over there.

If you are watching this repository, please feel free to comment on this and/or give a 👍 or 👎!

[KarelWintersky]

All my actual code required PHP 7+

You can drop support for PHP before 7 version :)

[cmfcmf]

I have now dropped support for PHP < 7 completely, since psr/http-client requires at least PHP 7.0. There are two things left for me to do before merging this PR and releasing 3.0.0:

• test the weather history data integration impossible because it requires a paid API key. I therefore removed weather history integration.
• use new PHP features (types, short array syntax, ...) postponed