Add extended tooltips

mods/HELP/tt/API.md

@@ -0,0 +1,33 @@
+# Tooltip API
+This API explains how to handle the extended item tooltips (`description` field).
+
+## Fields
+
+Add these to the item definition.
+
+* `_tt_ignore`: If `true`, the `description` of this item won't be altered at all
+* `_tt_help`: Custom help text
+* `_tt_food`: If `true`, item is a food item that can be consumed by the player
+* `_tt_food_hp`: Health increase (in HP) for player when consuming food item
+
+Once this mod had overwritten the `description` field of an item was overwritten, it will save the original (unaltered) `description` in the `_tt_original_description` field.
+
+## `tt.register_snippet(func)`
+
+Register a custom snippet function.
+`func` is a function of the form `func(itemstring)`.
+It will be called for (nearly) every itemstring.
+
+Returns: Two values, the first one is required.
+1st return value: A string you want to append to this item or `nil` if nothing shall be appended.
+2nd return value: If nil, `tt` will take of the text color. If a ColorString in `"#RRGGBB"` format, entire text is colorized in this color. Return `false` to force `tt` to not apply text any colorization (useful if you want to call `minetest.colorize` yourself.
+
+Example:
+
+```
+tt.register_snippet(function(itemstring)
+	if minetest.get_item_group(itemstring, "magic") == 1 then
+		return "This item is magic"
+	end
+end)
+```