AsI64 for i16, i8, u8

src/influx.rs

@@ -56,6 +56,9 @@ impl AsI64 for usize { fn as_i64(x: Self) -> i64 { x as i64 } }
 impl AsI64 for f64 { fn as_i64(x: Self) -> i64 { x as i64 } }
 impl AsI64 for f32 { fn as_i64(x: Self) -> i64 { x as i64 } }
 impl AsI64 for u16 { fn as_i64(x: Self) -> i64 { x as i64 } }
+impl AsI64 for i16 { fn as_i64(x: Self) -> i64 { x as i64 } }
+impl AsI64 for u8 { fn as_i64(x: Self) -> i64 { x as i64 } }
+impl AsI64 for i8 { fn as_i64(x: Self) -> i64 { x as i64 } }
 
 /// Created this so I know what types can be passed through the
 /// `measure!` macro, which used to convert with `as i64` and