* allow asn1 times of 1950-01-01 and later.

* add a test

* pretty up the test

Previously we used unix timestamps, but now we are switching to using
ASN1_TIME_set_string and automatically formatting the string based on
the year. The rule is as follows:

Per RFC 5280 (section 4.1.2.5.), the valid input time
strings should be encoded with the following rules:

1. UTC: YYMMDDHHMMSSZ, if YY < 50 (20YY) --> UTC: YYMMDDHHMMSSZ
2. UTC: YYMMDDHHMMSSZ, if YY >= 50 (19YY) --> UTC: YYMMDDHHMMSSZ
3. G'd: YYYYMMDDHHMMSSZ, if YYYY >= 2050 --> G'd: YYYYMMDDHHMMSSZ
4. G'd: YYYYMMDDHHMMSSZ, if YYYY < 2050 --> UTC: YYMMDDHHMMSSZ

Notably, Dates < 1950 are not valid UTCTime. At the moment we still
reject dates < Jan 1, 1970 in all cases but a followup PR can fix
that.

* add support for encoding compressed points

* review feedback

* shake128/256 support

* remove block_size

* doc an exception

* change how we detect XOF by adding _xof attribute

* interface!

* review feedback

* byteslike concatkdf

* byteslike scrypt

* byteslike x963kdf

* support byteslike in HKDF

* support byteslike in PBKDF2HMAC

* add missing docs