string float act like float when converted to int*

[yveshield]

#204 #172

built in: cast.ToInt64E(float64(8.2)) => 8

previously: cast.ToInt64E(string("8.2")) => unable to cast "8.2" of type string to int64

more expected: cast.ToInt64E(string("8.2")) => 8

If you agree with my thoughts or have a better understanding, feel free to leave a comment for discussion.