Improve serial plotter graph colors

Number of colors used by serial plotter increased from 4 to 8.
Improved colors (brighter; easy to tell apart):
blue, red, green, amber, purple, gray, aqua, black.

Author: cousteaulecommandant

Diff for: build/shared/lib/theme/theme.txt

@@ -37,16 +37,19 @@ buttons.status.font = SansSerif,plain,12
 buttons.status.color = #ffffff
 
 # GUI - PLOTTING
-# color cycle created via colorbrewer2.org
 plotting.bgcolor = #ffffff
 plotting.color = #ffffff
 plotting.gridcolor = #f0f0f0
 plotting.boundscolor = #000000
-plotting.graphcolor.size = 4
-plotting.graphcolor.00 = #2c7bb6
-plotting.graphcolor.01 = #fdae61
-plotting.graphcolor.02 = #d7191c
-plotting.graphcolor.03 = #abd9e9
+plotting.graphcolor.size = 8
+plotting.graphcolor.00 = #0000FF
+plotting.graphcolor.01 = #FF0000
+plotting.graphcolor.02 = #009900
+plotting.graphcolor.03 = #FF9900
+plotting.graphcolor.04 = #CC00CC
+plotting.graphcolor.05 = #666666
+plotting.graphcolor.06 = #00CCFF
+plotting.graphcolor.07 = #000000
 
 # GUI - LINESTATUS   
 linestatus.color = #ffffff