Preferences HTML cleanup (#3301)

changes:

Changed a lot of string building to use lists & Join() - this should reduce the number of strings generated at runtime.
Fixed a bug where the incidents menu was not populated.
Changed color boxes to use CSS & divs instead of one-cell tables.

code/modules/client/preference_setup/preference_setup.dm

@@ -7,6 +7,9 @@
 #define SQL_CHARACTER	0x1
 #define SQL_PREFERENCES	0x2
 
+// General-purpose helper for drawing a colored box.
+#define HTML_RECT(color) "&nbsp;<div style=\"display:inline;height:10px;width:30px;background:'[color || "#FFFFFF"]'\"></div>&nbsp;"
+
 /datum/category_group/player_setup_category/general_preferences
 	name = "General"
 	sort_order = 1