NeoPixel enhancements

This starts with Adafruit's NeoPixel library and reworks it a little to
enhance support for animations.

RgbColor.cpp

@@ -0,0 +1,89 @@
+/*--------------------------------------------------------------------
+NeoPixel is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation, either version 3 of
+the License, or (at your option) any later version.
+
+NeoPixel is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with NeoPixel.  If not, see
+<http://www.gnu.org/licenses/>.
+--------------------------------------------------------------------*/
+
+#include "RgbColor.h"
+
+uint8_t RgbColor::CalculateBrightness()
+{
+	return (uint8_t)(((uint16_t)R + (uint16_t)G + (uint16_t)B) / 3);
+}
+
+void RgbColor::Darken(uint8_t delta)
+{
+	if (R > delta)
+	{
+		R -= delta;
+	}
+	else
+	{
+		R = 0;
+	}
+
+	if (G > delta)
+	{
+		G -= delta;
+	}
+	else
+	{
+		G = 0;
+	}
+
+	if (B > delta)
+	{
+		B -= delta;
+	}
+	else
+	{
+		B = 0;
+	}
+}
+
+void RgbColor::Lighten(uint8_t delta)
+{
+	if (R < 255 - delta)
+	{
+		R += delta;
+	}
+	else
+	{
+		R = 255;
+	}
+
+	if (G < 255 - delta)
+	{
+		G += delta;
+	}
+	else
+	{
+		G = 255;
+	}
+
+	if (B < 255 - delta)
+	{
+		B += delta;
+	}
+	else
+	{
+		B = 255;
+	}
+}
+
+RgbColor RgbColor::LinearBlend(RgbColor left, RgbColor right, uint8_t progress)
+{
+	return RgbColor( left.R + ((right.R - left.R) * progress >> 8),
+		left.G + ((right.G - left.G) * progress >> 8),
+		left.B + ((right.B - left.B) * progress >> 8));
+}