adapting servo and pwm modes to work in nanoseconds

pwm range is no longer in value between 0 and 255, but in float value
between 0 and 100 that represents the duty cycle percentual
introduce analogWritens an tone functions

In the analogWrite function you can setting dutycycle and period in
nanoseconds. With the tone function you can work with buzzer.
introduced noTone and map functions, and upgrade tone function

noTone function allows to send a no sound frequency. Map function allows
to mapping a value in a different range. In tone function now is
possible specify the sound duration in milliseconds
Revert "introduced noTone and map functions, and upgrade tone function"

This reverts commit 06729850774166d1e365d536aa12633f9448a414.
Revert "Revert "introduced noTone and map functions, and upgrade tone function""

This reverts commit 3114e27af9d63462a3a8097e82f4d1e2c96c40dd.
upg: change tone function parameter and edit timers layout

introduced frequency parameter in tone function, and change key in
timers layout
upg: change return value of map function

return value is a float
Revert "upg: change return value of map function"

This reverts commit 0c8055fa77c48457f5741f4eddc73414e43414f5.
upgrade readme file
bug fix: readme file
update file readme
Merge pull request #6 from andrea-83/lininoIO

Linino io