Our fix in #37 has not worked: trying to decode the polyline `'ugh_ugh'` gives an out of bounds error on [line 142](https://github.com/georust/polyline/blob/bb74f6bfaa18e91ca504b1377ad02291e8d7eb09/src/lib.rs#L142): `index out of bounds: the len is 7 but the index is 7`.
