Add new option "activationDelay" + new function parameters + update documentation

## Add new option "activationDelay".
This option adds a delay (in milliseconds) before really opening submenu to prevent flickering submenus when moving cursor quickly between rows.
If this option is not set, no delay is applied.

## Add parameters to activate & deactivate functions
* Activate : add previously activated row as a second parameter if any.
* Deactivate : add next activated row as a second parameter if any.