Added option 'show_error_code'
Added mapping of PHP Errors, mapped to descriptions of them
Added display logic to displayError. I needed to add a parameter (the actual error code) so I've also amended the reportError(), where displayError() is called, to pass the error code.
Cosmetic changes: - Added H3 css class - Added #error-code css class - Moved the error code inside an H3, shown below the error-title.