Multi-file dive analysis

[clydemcqueen]

A dive may generate multiple telemetry (tlog) and dataflash (BIN) logs. These can be organized in a directory structure, with all of the log files for a dive sitting in a directory.

Create a dive.py tool that:

• opens all of the tlog and BIN files in a directory
• uses time information in the files (e.g., SYSTEM_TIME MAVLink messages) to build a single timeline that spans all of the telemetry and dataflash logs. The names of the files may also contain some useful information, though it may be less trustworthy than the data contained in the files.
• report any errors, such as missing log files
• print interesting information about the dive

The timeline generator should be in a separate Python file so that it can be used by other tools. E.g., merge.py may replace tlog_merge.py and BIN_merge.py and merge data from multiple files and log types.