Debug mode and translated data validation

Added functionality to validate translated product data before product update. If data is not valid, error message will be visible.
Fixed other errors visibility in project view page.
Implemented debug mode. Debug mode can be managed via URL in module BackOffice. If in URL exists parameter:
    &debug_on - debug mode is enabled and debug file URL appears on the screen;
    &debug_off - debug mode is disabled and debug file is deleted;
    &debug_delete - debug file is deleted.