Merge pull request#136 from peterdevpl/php8PHP 8 and PHPUnit 9 support

Merge pull request#134 from xchangeapi/feature/xchangeapicom-supportxChangeApi.com support

Updated Travis config

Making Swap class not final

Merge pull request#121 from florianv/newUpdated the documentation for the new version

Fixed documentation links

Merge pull request#105 from ddinchev/masterUpdate swap towards latest exchanger version.

Use the latest exchanger version

Merge pull request#92 from nadsrosun/hotfix-google-finance-providerUpdate to latest google finance endpoint

Merge pull request#91 from dannyweeks/add-cryptonator-serviceAdd Crypotonator service support