Whitelisting extras

I trust that the settings and restrictions caches deal with any performance issues and don't introduce any bugs. I haven't tested that aspect thoroughly, but it seems to work.

I have added a dialog in ActivityApp for managing the different types of whitelists. One aspect that might seem counter-intuitive is that you have to check to allow. This is similar to the allowed Accounts, Contacts and App, but dissimilar to the logic of restricting elsewhere. It might be wise to change this.

Currently the dialog uses the values of cWhitelistWhatever for the whitelist types, there is, as yet, no provision for using localised values.

Refs #1375