Access filter regex capture groups in custom template

[Fabi019]

There should be a way to address a specific capture group in a custom temlplate if more than one were defined in the regex filter.

Currently only the first group is extracted and can be used with the {CODE} template. Instead it should be possible to specify the index of the group.

For example: {CODE%2} to access the second capture group. When the group does not exist, there should be either a error or default to the whole code instead.