uc8151: improvements to speed and also add flicker-free mode based on @antirez code example

Signed-off-by: deadprogram <ron@hybridgroup.com>

uc8151/lut.go

@@ -0,0 +1,30 @@
+package uc8151
+
+// LUTType is the look-up table for the display
+type LUTType [42]uint8
+
+type LUTSet struct {
+	VCOM LUTType
+	WW   LUTType
+	BW   LUTType
+	WB   LUTType
+	BB   LUTType
+}
+
+func (lut *LUTType) Clear() {
+	for i := range lut {
+		lut[i] = 0
+	}
+}
+
+func (lut *LUTType) SetRow(row int, pat uint8, dur [4]uint8, rep uint8) error {
+	index := row * 6
+	lut[index] = pat
+	lut[index+1] = dur[0]
+	lut[index+2] = dur[1]
+	lut[index+3] = dur[2]
+	lut[index+4] = dur[3]
+	lut[index+5] = rep
+
+	return nil
+}