Feature: Dependency graph modifiable user regex

[jeremy-clerc]

For now when showing the dependency graph you can only choose all or the regex in the config. The idea would be to have a textfield to specify your regex expression.

[fgabolde]

I'm not sure allowing users to provide regexen is a good idea. I don't think there is a security risk in doing so, assuming we are not running in the scope of a use re 'eval' statement, but I'm not confident that a regex can't be crafted to e.g. cause an infinite loop.

I think if a custom filter can be provided by the user, then it should be simpler than a regex. Regular wildcards should be sufficient for most needs, so Foo-* becomes ^Foo-.*$ and *-Bar becomes ^.*-Bar$.