Remove Control Reset on Send

[dmadison]

This removes the control data reset that happens whenever the data is sent. The library now follows a more conventional "press/release" idiom, meaning that if you set a control surface it stays set up until you change it. E.g. if you set a joystick position it won't go back to 0 until you set it back to 0. This avoids having to write every possible control surface for every update, even if they don't change.

Because the array isn't cleared on every update, I also changed the "DPAD_UP" bit to "0" in the default array values. This way the controller won't hold the directional pad up if you don't overwrite the values.

[gdsports]

@dmadison @zlittell I merged PR #28, #30, #31 to my fork. The simple and flghtstick examples compile without problems using Arduino IDE 1.8.7 and Teensyduino 1.4.4. Looks very good.

[dmadison]

Glad to hear everything is working for you as well! It doesn't look like this repo is being maintained, so I'm going to continue development as needed on my fork.