file field bad when using std logger

[stephenmw]

Example:

package main

import "github.com/rs/xlog"

func main() {
    xlog.Error("what file is this?")
}

Output:

2016/04/16 22:51:18 ERRO what file is this? file=std.go:44

std.go:44 is xlog code: https://github.com/rs/xlog/blob/master/std.go#L44

Logger assumes that it is being called by the function with the error and not an intermediate function. This causes the file and line number to be taken from std.go instead of the client code.

[rs]

Good catch.