[Diagnostics] Further work on Flattened Exception. Lots of testing left to do.
Adding LICENSE files (MIT, as per each README and as noted in the respective composer.json files).
[Diagnostics] Fixing wrong namespace.
[Diagnostics/Debug] Let the fatal error handling onShutdown() method of the Error Handler also emit debug events.
[Diagnostics/Debug] Updating the Events Definition to make room for debug events specific to fatal errors.
[Diagnostics/Debug] Bring the event emission in handlers/FatalError::onShutdown() in line with the Events Definition.
[Diagnostics/Debug] Fix for PHP bug #65322.
[Diagnostics/Debug] Made Error Exception messages more human-friendly.
[Diagnostics/Debug] Added ClassNotFound and UndefinedFunction fatal error exceptions, soon to be thrown.