Documentation enrichment
Addition of some of the documentation [lis302dl - main - pedometer - spi1 - statistics - utility]

Signed-off-by: Omar Scotti <omar.scotti@mail.polimi.it>
Signed-off-by: Diego Rondelli <diego.rondelli@mail.polimi.it>
Fix comments

Signed-off-by: Omar Scotti <omar.scotti@mail.polimi.it>
Signed-off-by: Diego Rondelli <diego.rondelli@mail.polimi.it>
Fix function
Delete getCal()
Introduction of compareSteps()

Signed-off-by: Omar Scotti <omar.scotti@mail.polimi.it>
Signed-off-by: Diego Rondelli <diego.rondelli@mail.polimi.it>