Fixes #316 manually (unable to merge)
Fix #324
ConfigMaker should validate config no matter what
Widgets no longer need to pass their config via options:
Update CHANGELOG.md
Fix DocBlock

Being in a namespace of it's own, the type hint for $closure should be \closure (otherwise it assumes that it belongs in the ```System\Classes``` namespace)
Improve CMS Exception handler.
Previously Twig syntax errors inside a component partial would show the incorrect file and line number. This is fixed.
Also simplified the approach so the stack trace is not hidden inside a closure.
Commented out the refresh button, the usage is not 100% clear and can cause destructive damage.