[TYPO3-project-4-3] improve the errorhandling

[Rupert Germann]

hi,

here's a first patch for a better usable error handling using flashmessages.
(see screenshots)

I introduced a new TYPO3_CONF_VARS parameter:
$TYPO3_CONF_VARS['SYS']['errorHandlerErrors']

this parameter configures which errors reach the errorhandler.

$TYPO3_CONF_VARS['SYS']['exceptionalErrors'] is still used, it 
configures the errors which should be converted to an exception.

So we have 2 kind of errors: errorhandler errors and exceptionsl errors.

The default configuration looks like this:

'errorHandlerErrors'=> E_ALL ^ E_NOTICE,
'exceptionalErrors' => E_ALL ^ E_NOTICE ^ E_WARNING ^ E_USER_ERROR ^ 
E_USER_NOTICE ^ E_USER_WARNING

That means: everything but E_NOTICE reaches the errorhandler. But the 
errorhandler function throws only an exception on exceptional errors 
like e.g. E_RECOVERABLE_ERROR.

All non-exception errors are not printed directly but they are collected 
in an global array $GLOBALS['T3_VAR']['flashmessages'].
This happen in FE and BE.

During this I discovered that the current flashmessage handling is not 
very scalable because every "pushed" flasmessage causes a db 
select/insert operation which is incredibly slow if you have lot of 
these messages.
So I changed the functions pushFlashMessage/popFlashMessages in 
template.php to use $GLOBALS['T3_VAR']['flashmessages'] instead of 
storing the message in the db (all should work as before)
the patch contains this changes, too, but they will be a separate RFC of 
course.


to test this I made a little extension providing a be module and a fe 
plugin which can produce errors and exceptions. This extension is 
attached to this post.


Comments?

greets
rupert