Logger class

[Clovel]

We need to conceive a class to manage logs and that works similarly to std::cout or std::cerr. To do so, we need :

• [x] Class creation
• [x] Use of Serial.print & Serial.println functions on target
• [x] Use of iostream objects (std::cout, std::endl & std::cerr) in tests
• [x] << operator for :
  • [ ] Strings
  • [ ] Chars
  • [ ] Char arrays
  • [ ] int, long, short
• [ ] Doxygen documentation, as this class will be used everywhere