Add fallback_human() action to the Lua AI

Just like the FormulaAI fallback() function, this temporarily
transfers control of the side to a human player.

src/ai/lua/core.cpp

@@ -344,6 +344,11 @@ static int cfun_ai_check_recall(lua_State *L)
 	return ai_recall(L, false);
 }
 
+static int cfun_ai_fallback_human(lua_State*)
+{
+	throw fallback_ai_to_human_exception();
+}
+
 // Goals and targets
 
 
@@ -971,6 +976,7 @@ static int impl_ai_get(lua_State* L)
 			{ "stopunit_attacks", &cfun_ai_execute_stopunit_attacks },
 			{ "stopunit_moves", &cfun_ai_execute_stopunit_moves },
 			{ "synced_command", &cfun_ai_execute_synced_command },
+			{ "fallback_human", &cfun_ai_fallback_human},
 			{ nullptr, nullptr } };
 	for (const luaL_Reg* p = mutating_callbacks; p->name; ++p) {
 		if(m == p->name) {

src/menu_events.hpp

@@ -19,6 +19,7 @@
 #include "chat_events.hpp"
 #include "floating_textbox.hpp"
 #include "units/map.hpp"
+#include "lua_jailbreak_exception.hpp"
 
 #include <vector>
 
@@ -35,7 +36,7 @@ namespace events {
 	class mouse_handler;
 }
 
-struct fallback_ai_to_human_exception {};
+struct fallback_ai_to_human_exception : public lua_jailbreak_exception {IMPLEMENT_LUA_JAILBREAK_EXCEPTION(fallback_ai_to_human_exception)};
 
 namespace events {