Updated to PHP 7.4 and PHPUnit 9

3.0

Merge remote-tracking branch 'ariadne/master'

Updated dependencies

Now uses the correct exception names

Now works with arc-base 2

Merge pull request #11 from poef/master

updated requirements to accept arc-base 2

arc-events: code style cleanup and documentation fixes

code style more to PSR-2
documentation and project info fixes