lua_function= in SUF now has limited support for non-global functions

To be precise, the string is considered as a dot-separated list of components.

changelog

@@ -21,6 +21,8 @@ Version 1.13.4+dev:
    * Weapon filters now support number, parry, accuracy, and movement_used
    * New [has_attack] in standard unit filters; supercedes has_weapon= and
      uses full weapon filter.
+   * lua_function=var.member now works in SUF; however, 'var' still needs to
+     be a global variable.
    * AiWML:
      * Simplified aspect syntax which works for all aspects, present and future:
        * All aspects with simple values can be specified as key=value

src/scripting/game_lua_kernel.cpp

@@ -4896,7 +4896,8 @@ bool game_lua_kernel::run_filter(char const *name, unit const &u)
 	if (!ui.valid()) return false;
 
 	// Get the user filter by name.
-	if(!luaW_getglobal(L, name))
+	const std::vector<std::string>& path = utils::split(name, '.', utils::STRIP_SPACES);
+	if(!luaW_getglobal(L, path))
 	{
 		std::string message = std::string() + "function " + name + " not found";
 		log_error(message.c_str(), "Lua SUF Error");