fixed 3853: Don't log $context given on error handler as extras because it contains an array of ALL global variables incl. super globals
Copy the static $errorPriorityMap to a scoped variable with the same name and use it within the error/exception handler
fixed 4456: call register[Error|Exception]Handler with static instad of self to make it possible overwrite the methods but using the auto register logger options
Merge pull request #4609 from marc-mabe/hotfix/3853

Logger: Error/Exception Handler: fixed 3853 & 4456
Merge branch 'hotfix/4609'

Close #4609
Fixes #3853
Fixes #4456
Fixes #4503