Quantity of servos possible uses more memory than necessary for most

If you change the header then the default quantity of servos possible (254) could be reduced to reduce the memory footprint. 
Normally I put an ifndef in front of that type of thing to allow a global to redefine it but it could also be done as global defines to select tested values that limit the testing needed (SMALL as 4, MEDIUM as 16, LARGE as 254, etc).