Additional bytevector utilities.

`(bytevector-u16-ref-le bv i)`

Retrieve a 16-bit unsigned integer value from the given bytevector
`bv`

at offset `i`

, in little-endian order.

`(bytevector-u16-ref-be bv i)`

Retrieve a 16-bit unsigned integer value from the given bytevector
`bv`

at offset `i`

, in big-endian order.

`(bytevector-u32-ref-le bv i)`

Retrieve a 32-bit unsigned integer value from the given bytevector
`bv`

at offset `i`

, in little-endian order.

`(bytevector-u32-ref-be bv i)`

Retrieve a 32-bit unsigned integer value from the given bytevector
`bv`

at offset `i`

, in big-endian order.

`(bytevector-ber-ref bv [i end])`

A BER compressed integer (X.209) is an unsigned integer in base 128,
most significant digit first, where the high bit is set on all but the
final (least significant) byte. Thus any size integer can be
encoded, but the encoding is efficient and small integers don't take
up any more space than they would in normal char/short/int encodings.

`(bytevector-ber-set! bv n [start end])`

Convert an unsigned integer `n`

to a bytevector representing
the base-256 big-endian form (the zero index holds the MSB).

The inverse of `integer->bytevector`

. Convert a bytevector
representing the base-256 big-endian form (the zero index holds
the MSB) to the corresponding unsigned integer.

`(bytevector-pad-left bv len)`

Utility to pad a bytevector with zeros. Padding is added to the
left so as not to change the big-endian value.

Big-endian conversion, guaranteed padded to even length.

`(hex-string->integer str)`

`(bytevector->hex-string bv)`

`(hex-string->bytevector str)`