Separated servod.c to servod.c/.h and main.c files, Makefile updated.
Servo properties consolidated to servo_t typedef.
New command line --min-max added to calibrate min/max width per servo:
    --min-max=servo:min-max{N|Nus|N%},servo:min-max{N|Nus|N%}
For example:
    --min=50 --max=280 --min-max=0:58-265,1:60-278
Get/set writes to /dev/servoblaster can accept comma separated list:
    echo 0=50%,1=10% > /dev/servoblaster
    echo 1=?%,0=?%