Implement improved ignore list

[hlubek]

Goals:

• Deprecate "blacklist" because of inappropriate naming (but still accept the old configuration option to keep it compatible)
• Use "ignorelist" as the new name (configuration options and classes)
• Extend exception ignore lists based on:
  • Message regexp
  • Class regexp -> provide examples due to escaping / backslashes
  • Exception code
• Document example to readme

This way we could configure a common list of "client" exceptions that cause too much noise in Sentry and are due to e.g. bad route parameters, property mapping or form validation.

[baschny]

In the long run it would be cool to implement black/whitelist of log entries directly in TYPO3 core instead that each client / LogWriter inventing their own settings. So we could use this also for the FileWriter and other logging services.

[christophlehmann]

To be ignored Exception codes should go into core if possible

[christophlehmann]

Exception classes can now be ignored with ignore_exceptions