DateTime can now be parsed from a string. Implements the same formatters
as strptime: https://linux.die.net/man/3/strptime (Well, some of them at
least).
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
