Create a custom Logger instance instead of using root one

[lorenz-gorini]

In pytrousse repo, the root Logger instance is used in each module.
This may prevent the pytrousse user to set up a custom logger for pytrousse package, without modifying the root logging instance.

A possible solution could be to create a unique custom logger for pytrousse package that is used by each module, inserting at the beginning of each module the following line:

logger = logging.getLogger(TROUSSE_LOGGER_NAME)

and replacing each root logging instance call with logger one.
For example:

logging.info("My message")

could be replaced by:

logger.info("My message")