Create UNSET enum

[BobbyMi11er]

Fixes #25
I added the enum but I'm pretty sure this is just adding another layer of abstraction for a NPE error.

[ArchdukeTim]

There shouldn't be an NPE anywhere with this, but somewhere you should be checking to see if the color is UNSET. I think there's somewhere in the code where there's a null check? Maybe one should go before here:

2020-offseason/src/main/java/frc/robot/commands/ControlPanelColorCommand.java

Line 38 in c8b5beb

double direction = Math.signum(turnToColor.ordinal() - controlPanel.getControlPanelColor().ordinal());

and maybe also a check in the isFinished method?

[ArchdukeTim]

All of this color sensing code seems very complex. I wonder if there's a way to simplify it.

[AndrewLester]

I agree with Tim that it's surprising no if statements that previously checked for null have to be changed to UNSET. It might be that we'll have a use for it when we bind the Control Panel Color Spin command to a button.

[ArchdukeTim]

I would actually make this UNKNOWN rather than UNSET because without context, if a color isn't one of those it's uknown. Only in the context of the driverstation sending a color is it unset. It'll also make sense if you return UNKNOWN when the confidence for the color matcher is low, whereas UNSET wouldn't make as much sense in that context

[ArchdukeTim]

And I think you should give it a default value of either 0,0,0 or 1,1,1. Setting null will cause an NPE when the color matcher tries to match to it.

[AndrewLester]

Actually I do realize now that the addition of the UNSET/UNKNOWN constant would break the math for the turn to color calculation. I have an idea on how to simplify the Color/Colorsenor classes but I'll make an issue for that.