Calculates flood paths.
(tpm_traceflood trace_id start maxres)
Returns T or nil.
| trace_id | Tracing model ID, returned by tpm_tracealloc (real) |
| start | Element ID of start node (real) |
| maxres | Maximum allowed accumulated path resistance (real) |
The accumulated resistance value is the total resistance of the nodes and links that make up the flood trace.