Introduce builtin function: type

[xushiwei]

In Go, we use reflect.TypeOf to get type of a value:

tyInt := reflect.TypeOf(int(0))
tyEmptyInterface := reflect.TypeOf((*interface{})(nil)).Elem() // no easy way to get an interface type

We may can introduce a type function to simplify it:

tyInt := type(int)
tyEmptyInterface := type(interface{})

[JessonChan]

mayb be typeOf is an alternate choice. But I'm not very sure about this feature, it seems not very necessary.

[JessonChan]

we can move this faction to another lib package, like "reflects".

[xushiwei]

we can move this faction to another lib package, like "reflects".

Because we use types as parameters, it is not a normal function. It has to be a builtin function like new.