Request: allow regexp in icon customization

[rolling-robot]

I have top-level accounts that are associated with asset type, such as deposit, stocks, bonds, etc. Second or third level is the name of bank that provides me an account. I think this is quite common scenario.

I want the icons to correspond to the bank in which I have an account. Now I have to specify a number of entries with the same icon to achieve that.

It may be useful to have a regexp for account name instead of the actual account name to choose an appropriate icon for that use case.