0.4.0 PHP 7.2

• 7e3982e require broadway/broadway ^2.3.1 (othillo)
• 0402b74 set branch alias to 1.0.x-dev (othillo)
• 6c5a43e add license (othillo)
• 0b18f67 broadway/coding-standard ^1.0 (othillo)
• 2f38391 remove Travis branch restriction (othillo)
• 91ea66a PHPStan level max (othillo)
• ac25be1 added license (othillo)
• 1f4c9cc changelog in Makefile (othillo)
• 7d0b8cd use Makefile in Travis CI (othillo)
• e1bdc70 remove syntaxCheck (othillo)
• aac8040 Makefile (othillo)
• 9f608fb require broadway/broadway ^2.2.1 (othillo)
• 251927b applied coding standard (othillo)
• 366adbb PHPUnit 8 (othillo)
• 932151c require php >= 7.2 (othillo)
• 98bbaee only test actively supported PHP versions (othillo)
• 31365f6 configured Stale bot (othillo)
• 8868bd7 Adjusted PHP version (do not support 7.0 any more and add 7.3). (othillo)
• 9bb3d26 Fixed missing return type that caused a fatal PHP error. (othillo)