I can see there's an exclusion list, but is there an easy way of telling Avast to ignore a virus and let the user use that file, if the user chooses to do so, and then set it to always ignore it?
Indeed there are
two Exclusion lists:
For the
Standard Shield provider (on-access scanning):
Left click the 'a' blue icon, click on the provider icon at left and then Customize.
Go to Advanced tab and click on Add button...
For the other providers (
on-demand scanning such as the screen-saver or the Simple User Interface):
Right click the 'a' blue icon, click Program Settings.
Go to Exclusions tab and click on Add button...
You can use wildcards like * and ?.
But be careful, you should 'exclude' that many files that let your system in danger.