书ļĺӿ˵:
int valid_enable(string usage);
	 enalbe, jifa 
	usage ǻ书Ӣ
	书 usage 书򷵻 1

int valid_combine(string combo);
	 prepare, bei 
	ֻȭ书
	combo һ书Ӣ
	书Ժ combo һʹ򷵻 1

int valid_learn(object me);
	 learn, xue, pratice, lian 
	me ҵı
	ҷѧϰ书򷵻 1

int practice_skill(object me);
	 pratice, lian , ˳ valid_learn ֮
	 valid_lean  0 úᱻõ
	һڸúжÿһϰĽп۳
	ҷϰ书򷵻 1
	[1;33m¸ĶֵΪ 1 ʾϱ׼书[0;37;0m
	[1;33mֵ > 1 ʾֵ书[0;37;0m

string query_skill_name(int level);
	ؼ level ʱʽ

mapping query_action(object me, object weapon);
	սϵͳ
	书еĺ
	ֵΪ, սᱨ
	ֵĺ
	([
		"action": "...",	// ʽ
		"dodge" : xxx,		// һжԽӰ
		"damage": xxx,		// һֻ书
					// ֵҪ˺
		"force" : xxx,		// ֵҪͽĺ
		"damage_type": "...",	// ˺͵
	])
	ֵǹϵͳõ, 书ļⶨҪĲ

string query_dodge_msg(object me);
	ֵṦ

string perform_action_file(string action);
	 perform 
	action  perform Ĳ
	ִֵи perform ļ

mixed hit_ob(object me, object victim, int damage_bonus);
	ʹø书Ŀʱ
	me ǹ, victim ǱеĿ, damage_bonus ĿѾܵ
	˺ĵ
	ֵ string , ʾڹ֮
	ֵ int , ӵ damage_bonus 
