[stewartadam]

Problem

With announce_timeout enabled, check_seq_number ran the global timeout check and returned the first UniverseTimeout it found. That error replaced the result for the packet being checked, so a valid packet from source A was dropped whenever some other source B had timed out.

Fix

• SacnReceiver::recv already runs the timeout check (and announces timeouts) before every socket read. check_seq_number now only prunes timed-out entries itself when timeouts are not being announced.
• If the packet's own source/universe entry has timed out but hasn't been removed yet, it's treated as a new universe for that source. Otherwise a source that restarts its sequence could be rejected as out of sequence.

Tests

Two unit tests in receive.rs:

• an in-sequence packet is accepted while another source's entry has expired, and the expired entry is left for recv to report;
• a packet after the source's own entry expired is accepted even though its sequence number falls in the discard window.

cargo test --lib passes.

This touches the same function as the fix for the inverted break in check_timeouts. That fix changes a different part of the file, so the two shouldn't conflict.