ROOTObjectWriter: allow waiving sequence requirement

* `file_name` : Name of the data file to create, relative to the output directory of the framework. The file extension `.root` will be appended if not present.

* `include` : Array of object names (without `allpix::` prefix) to write to the ROOT trees, all other object names are ignored (cannot be used together simultaneously with the *exclude* parameter).

* `exclude`: Array of object names (without `allpix::` prefix) that are not written to the ROOT trees (cannot be used together simultaneously with the *include* parameter).

* `require_sequence`: Boolean flag to select whether events have to be written in sequential order or can be stored in the order of processing. Defaults to `true`, writing events in the order they have been seeded. If strict adherence to the order of events is required, finished events are buffered until they can be written to file.

## Usage

To create the default file (with the name *data.root*) containing trees for all objects except for PropagatedCharges, the following configuration can be placed at the end of the main configuration:

    // Bind to all messages with filter

    messenger_->registerFilter(this, &ROOTObjectWriterModule::filter);

    // Waive sequence requirement if requested by user

    config_.setDefault("require_sequence", true);

    if(!config_.get<bool>("require_sequence")) {

        waive_sequence_requirement();

    }

}

/**

 * @note Objects cannot be stored in smart pointers due to internal ROOT logic