Implement break and continue for loops

[mertyildiran]

Implement break and continue keywords for loops. These keywords should only be usable inside decision blocks like:

num def add(num x, num y)
    num z = x + y
end {
    z == 8  : continue,
    z > 10  : break,
    default : f3()
}

and such functions that utilizes these keywords, should automatically be recognized as looping functions therefore can only be called inside loop. If such function is called outside loop then an error must be thrown.