blurhash panics on parsing crafted inputs

blurhash-rs is a pure Rust implementation of Blurhash, software for encoding images into ASCII strings that can be turned into a gradient of colors representing the original image. In version 0.1.1, the blurhash parsing code may panic due to multiple panic-guarded out-of-bounds accesses on untrusted input. In a typical deployment, this may get triggered by feeding a maliciously crafted blurhashes over the network. These may include UTF-8 compliant strings containing multi-byte UTF-8 characters. A patch is available in version 0.2.0, which requires user intervention because of slight API churn. No known workarounds are available.