Introduce new log format to improve logging performances

[gergondet]

This PR changes the way the log information is stored in the log.

• Record the callback type only once
  • Small reduction in output size
  • Small reduction in logging workload at runtime
  • Slightly higher complexity for parsing the output
  • Pave the way to events' logging
• Run through the callbacks in the order they were called
  • Required by the parser to reconstruct correctly
  • Better cache locality (maybe?)

Overall, it improves the logging performance by about 25% on e.g. BaseLineWalkingController

Old logs are still compatible with all the tools in the framework.