Provide palettes as functions

Change-Id: Idc93e5c4538233ceaf248530e98a20cdcac38764
diff --git a/NAMESPACE b/NAMESPACE
index f3d776b..e97eb00 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -3,6 +3,9 @@
 export(hc_theme_ids_dark)
 export(hc_theme_ids_light)
 export(hc_theme_ids_mono)
+export(idsPalette)
+export(idsPaletteD3)
+export(idsPaletteGreyscale)
 export(ids_pal)
 export(scale_color_ids)
 export(scale_colour_ids)