test file was .. misnamed :|
Add merge option to InstanceConfig trait

This addresses the problem raised in b81ebffe
merge by default
make config chainable
Don't merge events

This is one of the exceptions where merging is not likely to be the
desired behavior - it would mean that you can't configure to disable
default events, it'd require code calls
change proxied config function to return the helper

On write options to modify templates - return $this instead of the
templater object
correct constructor and write expectations
Merge pull request #3134 from AD7six/3.0-form-auth-config-fix

Add possibility to merge config to InstanceConfigTrait