Change API of callAll function to support explicit selection of class name

[bheisen]

Is your feature request related to a problem? Please describe.
When using a regex for defining a class name in a managing backend, there is not way to use the callAll function on it.

Describe the solution you'd like
It would be nice to explicitly perform a callAll on e.g. a base-class while leaving a regex to listen to all derived ones.

[create-issue-branch]

Branch feature/34-change-api-of-callall-function-to-support-explicit-selection-of-class-name created!