TLog Playback Broken for Multiple Component IDs.

#### Issue details
Playback of telemetry logs (recorded by Mission Planner) which contain messages from more than one component ID seems to fail. The failure mode is that during playback, nothing visible happens, even though the playback progress bar advances as expected. While playback of the raw file fails, if we then run the file through an external utility which removes all the MAVLink messages not coming from cID 1, then the resulting file plays as expected, so it seems to be the presence of some message from another MAVLink component in the file is the cause of the issue. Not sure whether it's a specific message, or just the presence of messages from other components in general.

#### Version
1.3.4 and 1.3.52 are affected, haven't tested anything before 1.3.4.

#### Platform
[ ] All
[ ] AntennaTracker
[x] Copter
[ ] Plane
[ ] Rover
[ ] Sub

#### Airframe type
Quad

#### Hardware type
Pixhawk V2.1

#### Logs
Can't share the original log due to commercial sensitivity. Should be straight-forward to replicate though.

Start by reproducing playback with a telemetry log containing messages from multiple component IDs, then compare it with the cID 1-only version described in the issue. Trace the playback path to identify where non-cID 1 messages affect processing; done means multi-component logs display telemetry during playback instead of only advancing the progress bar.

Written by the indexing model from the issue text.