Base: Add pastel color palette

Add pastel color palette for PixelPaint.

Base/res/color-palettes/pastel.palette

@@ -0,0 +1,14 @@
+#8f8f8f
+#d6d6d6
+#ffc3c3
+#ffc3a5
+#ffe7a6
+#d4ffa6
+#adffa5
+#a5ffd4
+#a5fff1
+#a6d2ff
+#a6aeff
+#caa6ff
+#f3a5ff
+#ffa6e9