[isf-wifidog] event logging class checkin

[Rob Janes]

Benoit, Francois-

of the code i've been writing, the event logging stuff seemed the most 
welcome, so I just checked that in at the head.  seemed like a harmless 
thing to do.  i hope that's hunky dorry.

to use it, for example, put this after the require_once(...) in index.php:

require_once BASEPATH.'classes/EventLogging.php';

EventLogging::SetupErrorHandling(null, new PrintChannel(new 
HTMLFormatter(), 'warning,notice', null, true), new PrintChannel(new 
HTMLCommentsFormatter(), '=debug', null, true));

that's all.  The "true" flag tells the print channel to put all messages 
on a hold queue.

the object's destructor will cause any unwritten messages to be 
flushed.  the message text appears after the closing </html> tag, which 
seems to be rendered ok in firefox.  not sure about ie.

i need to add more docs to the class.

i'm still working on the install scripts.  saying i'd have it checked in 
(on a "rob" branch) last weekend was too optimistic i guess.

cheers
rob