Merge branch 'master' into jgrpp

# Conflicts:
#	CMakeLists.txt
#	bin/ai/CMakeLists.txt
#	bin/game/CMakeLists.txt
#	src/ai/ai_info.cpp
#	src/company_base.h
#	src/economy.cpp
#	src/game/game_info.cpp
#	src/gfx_type.h
#	src/linkgraph/linkgraph_gui.cpp
#	src/palette.cpp
#	src/palette_func.h
#	src/saveload/saveload.h
#	src/saveload/vehicle_sl.cpp
#	src/ship_cmd.cpp
#	src/train_cmd.cpp
#	src/vehicle_base.h
#	src/window.cpp
#	src/window_func.h

src/palette_func.h

@@ -10,6 +10,7 @@
 #ifndef PALETTE_FUNC_H
 #define PALETTE_FUNC_H
 
+#include "core/enum_type.hpp"
 #include "gfx_type.h"
 
 extern Palette _cur_palette; ///< Current palette
@@ -36,13 +37,25 @@ inline bool IsValidColours(Colours colours)
 
 TextColour GetContrastColour(uint8_t background, uint8_t threshold = 128);
 
-/**
- * All 16 colour gradients
- * 8 colours per gradient from darkest (0) to lightest (7)
- */
-extern byte _colour_gradient[COLOUR_END][8];
 extern byte _colour_value[COLOUR_END];
 
+enum ColourShade : uint8_t {
+	SHADE_BEGIN = 0,
+	SHADE_DARKEST = SHADE_BEGIN,
+	SHADE_DARKER,
+	SHADE_DARK,
+	SHADE_NORMAL,
+	SHADE_LIGHT,
+	SHADE_LIGHTER,
+	SHADE_LIGHTEST,
+	SHADE_LIGHTEREST,
+	SHADE_END,
+};
+DECLARE_POSTFIX_INCREMENT(ColourShade)
+
+byte GetColourGradient(Colours colour, ColourShade shade);
+void SetColourGradient(Colours colour, ColourShade shade, byte palette_colour);
+
 /**
  * Return the colour for a particular greyscale level.
  * @param level Intensity, 0 = black, 15 = white