dialogxml parseColor use a map built from Colours constants

parseColor() was doing a big if-else with string comparisons,
and returning values that differed from our Colours constants.
Since I couldn't find an instance of the colour attribute in our
existing xml, it should be safe to do away with those conflicting
values and refactor parseColor() to match the constants
and use cleaner code.

src/gfx/render_shapes.cpp

@@ -17,6 +17,27 @@
 using boost::math::constants::pi;
 using pt_idx_t = decltype(((sf::Shape*)nullptr)->getPointCount());
 
+std::map<std::string,sf::Color> colour_map = {
+	{"white", Colours::WHITE},
+	{"black", Colours::BLACK},
+	{"grey", Colours::GREY},
+	{"gray", Colours::GREY},
+	{"red", Colours::RED},
+	{"green", Colours::GREEN},
+	{"blue", Colours::BLUE},
+	{"teal", Colours::TEAL},
+	{"pink", Colours::PINK},
+	{"yellow", Colours::YELLOW},
+	{"orange", Colours::ORANGE},
+	{"shadow", Colours::SHADOW},
+	{"title_blue", Colours::TITLE_BLUE},
+	{"navy", Colours::NAVY},
+	{"dark_blue", Colours::DARK_BLUE},
+	{"dark_green", Colours::DARK_GREEN},
+	{"light_green", Colours::LIGHT_GREEN},
+	{"dark_red", Colours::DARK_RED}
+};
+
 // TODO: Put these classes in a header?
 class EllipseShape : public sf::Shape {
 	float divSz;

src/gfx/render_shapes.hpp

@@ -11,6 +11,7 @@
 
 #include <vector>
 #include <memory>
+#include <map>
 #include <SFML/Graphics/Shape.hpp>
 #include "location.hpp"