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 *
This commit adds a fully functional DEFLATE compression
implementation that can be used to implement compression
for higher level formats like gzip, zlib or zip.
A large part of this commit is based on Hans Wennborg's
great article about the DEFLATE and zip specifications:
https://www.hanshq.net/zip.html
