correct bug in price delete

Created function to retrieve total discounted amount of a commonobject

Created a modular syslog handler system

Normalized thirdparties module card name

I've split all log handlers into classes so that people can make
new log handler systems without making changes to the core.
Also, now every log handler can handle how and what will be logged.

manually into llx_bank).

Fixed PHP warning on MailmanSPIP module