Create wrapper functions for writing to each servo

[Chana030102]

For portability, create a wrapper function for each servo to write to them. The write method can then be changed within this function when implementing with different hardware, but won't break compatibility with other functions (semaphore, Kinect, etc).

These functions should also implement degree standards and apply transformations to input degrees.

[Chana030102]

Closing because we can do this with the provided functions in the library. There is a sketch that demonstrates this in "example" folder.

[halyngoc]

Reopen since I think having wrappers makes sense. Maybe sometimes we need to move one specific servo for testing purposes and it's more convenient to have a function for that instead of going through Pose. And the library function setPWN(channel, on, off) doesn't look very friendly.