In the initial implementation, infected file cleanup and exception throwing
was done at the plugin level. This is somewhat incorrect from plugin
responsibility perspective. The patch moves cleanup and exception logic to
the manager. Antivirus plugin responsibility is limited to perform scanning
and respond with one of the result statuses defined in the
\core\antivirus\scanner.
This implements the use of class autoloading for antivirus plugin. Base
abstract class, exception class and manager are using namespace
core\antivirus, this is because all three class files are located in
/lib/classes/antivirus/ (see \core_component::classloader for convention
details).
