Merging gateways are not modeled in a "new column"

[till-stadtler]

Describe the Bug

This example shows two cases of merging gateways not getting a "new column" to allow the incoming sequence flows to not cross other elements.

Steps to Reproduce

1. Navigate to https://bpmn-io.github.io/bpmn-auto-layout/
2. Model the process displayed above.

Expected Behavior

I expect merging gateways/elements to receive a new column if appropriate so incoming sequence flows do not cross other elements.

Environment

https://bpmn-io.github.io/bpmn-auto-layout/

[abdul99ahad]

Adding to ready state.