mavlogdump: CSV option: Don't cut out messages with same timestamp

[shancock884]

The PR is to fix #905.

It removes the logic which cuts out subsequent messages from CSV output if they have the same timestamp.
This typically affects messages with instances like IMU, where only the last one of a sequence would be output.
It would also affect messages like MSG, MULT, UNIT, etc, which may be added to the log file in batch.

Main Testing

I have tried a few files, with a few message types, and can now see expected output. For example, the IMU data for both instances even when they have the same timestamp:

$ mavlogdump.py --format=csv --types=IMU ArduPlane-Soaring-00000045.BIN
timestamp,TimeUS,I,GyrX,GyrY,GyrZ,AccX,AccY,AccZ,EG,EA,T,GH,AH,GHz,AHz
1704628006.74000502,1745135,1,-0.00015193763829302043,9.939412120729685e-05,-3.919340451830067e-05,-0.0009788739262148738,-0.00279411138035357,-9.817838668823242,0,0,25.10784149169922,1,1,760,799
1704628006.75999689,1765127,0,-3.0728398996870965e-05,-6.79766817484051e-05,1.5066639207361732e-05,-0.00010934187594102696,-0.0010120467050001025,-9.816944122314453,0,0,25.109102249145508,1,1,999,999
1704628006.75999689,1765127,1,-0.00019223210983909667,-1.3705200217373203e-05,0.00017314731667283922,-0.002659626305103302,0.0018529330845922232,-9.819148063659668,0,0,25.109167098999023,1,1,760,799
1704628006.77998900,1785119,0,6.50839792797342e-05,-2.898311140597798e-05,2.255062645417638e-05,-0.001452248776331544,-0.0007089077262207866,-9.817065238952637,0,0,25.110427856445312,1,1,999,999
1704628006.77998900,1785119,1,0.0001738743158057332,0.00016524168313480914,1.77201673068339e-05,-0.0001426656381227076,0.0013984335819259286,-9.817688941955566,0,0,25.11049461364746,1,1,760,799
...

Additional Testing/Fixes

Testing with DF Text logs found that outputting a text log to CSV was throwing an error.
This has been fixed by using (isbin or islog) in place of isbin in a couple of the if statements.

When specifying a message type that doesn't exist, an exception was being thrown, so I have added some checks to output a nicer message for users in this case:

$ mavlogdump.py --format=csv --types=aaa ArduCopter-ArmFeatures-autotest-1705041782499410.tlog
Message type 'aaa' not found
$ mavlogdump.py --format=csv --types=aaa ArduPlane-Soaring-00000045.BIN 
Specified type 'aaa' not found in log file
$ mavlogdump.py --format=csv --types=aaa ArduPlane-Soaring-00000045.log 
Specified type 'aaa' not found in log file

Behaviour with TLOGs

When dumping TLOGs to CSV, it is allowed to specify multiple messages in the --type argument. This outputs data for the message at that timestamp, and empty fields for the others (shown below).
This may look a bit odd, and I don't know if it is what was intended, but my change doesn't appear to have altered the behaviour, so I was thinking not to touch it. The previous logic would only ever have merged messages onto one line if they had identical timestamps to the microsecond level - which doesn't sound possible!

$ mavlogdump.py --format=csv --types=SYS_STATUS,HEARTBEAT ArduCopter-ArmFeatures-autotest-1705041782499410.tlog
timestamp,SYS_STATUS.onboard_control_sensors_present,SYS_STATUS.onboard_control_sensors_enabled,SYS_STATUS.onboard_control_sensors_health,SYS_STATUS.load,SYS_STATUS.voltage_battery,SYS_STATUS.current_battery,SYS_STATUS.battery_remaining,SYS_STATUS.drop_rate_comm,SYS_STATUS.errors_comm,SYS_STATUS.errors_count1,SYS_STATUS.errors_count2,SYS_STATUS.errors_count3,SYS_STATUS.errors_count4,HEARTBEAT.type,HEARTBEAT.autopilot,HEARTBEAT.base_mode,HEARTBEAT.custom_mode,HEARTBEAT.system_status,HEARTBEAT.mavlink_version
1705041782.55857992,,,,,,,,,,,,,,10,3,65,16,2,3
1705041782.57506800,,,,,,,,,,,,,,10,3,65,0,4,3
1705041782.57640886,321969423,268468495,51413263,0,0,-1,-1,0,0,0,0,0,0,,,,,,
1705041782.57741690,,,,,,,,,,,,,,6,8,0,0,0,3
1705041782.57862782,321969423,268468495,51413263,0,0,-1,-1,0,0,0,0,0,0,,,,,,
1705041782.57950497,,,,,,,,,,,,,,6,8,0,0,0,3
...

[peterbarker]

You can probably use --condition to trim down to only a single instance of the (e.g.) IMU message

[peterbarker]

Merged, thanks!