ezmodule template operator returns true even if the module isn't registered.

This seems a little wrong. How should a design check if a module is available?

ezmodule should basically also check ModuleList before it checks deny rules to make it usefull for extensions.

Steps to reproduce

{def $moduleExists = ezmodule( 'non_existant_module' )}
{if $moduleExists}
    ezmodule doesn't work
{else}
    ezmodule works
{/if}