wea.table_map(): Add api function

worldeditadditions/utils/tables.lua

@@ -65,3 +65,17 @@ function worldeditadditions.table_tostring(tbl, sep, new_line)
     end
     return ret:concat("")
 end
+
+--- Executes the given function on every item in the given table.
+-- Ignores return values that are nil and doesn't insert them into the table.
+-- @param	tbl		table		The table to operate on.
+-- @param	func	function	The function to execute on every item in the table.
+-- @returns	table	A new table containing the return values of the function.
+function worldeditadditions.table_map(tbl, func)
+	local result = {}
+	for i,value in ipairs(tbl) do
+		local newval = func(value, i)
+		if newval ~= nil then table.insert(tbl, newval) end
+	end
+end
+