Support `static` keyword

[vuryleo]

Only for that a:static int won't work.

[curimit]

If you not declare static int inside function body, you can just set static as an attribute. Maybe it is not good to define static variable inside function body. But any way I add this for addition syntax.

import "iostream"

using namespace std

[static]
x: int

x: static int

class Test
    [static]
    x: int

int main()
    a:static int