GEAR sink: Add io outputs
This MR adds new fields in snapshots and prints a new message when gas particles form sinks. I've also added a page in the doc to explain the fields the sink writes in snapshots. I will help users and developers.
This MR adds new fields in snapshots and prints a new message when gas particles form sinks. I've also added a page in the doc to explain the fields the sink writes in snapshots. I will help users and developers.