Yellow squiggly lines begone!
Done automatically on .cpp files through `run-clang-tidy`, with manual corrections to the mistakes.
If an import is directly used, but is technically unnecessary since it's recursively imported by something else, it is *not* removed.
The tool doesn't touch .h files, so I did some of them by hand while fixing errors due to old recursive imports.
Not everything is removed, but the cleanup should be substantial enough.
Because this done on Linux, code that isn't used on it is mostly untouched.
(Hopefully no open PR is depending on these imports...)

Kill Renderer (with phire)

I think this is only used for texture dumping, but this resolves some failed assertions and glitchy results.

SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.

Fixes issue 11393.

The problem is that left and top make no sense for a width by height array; they only make sense in a larger array where from which a smaller part is extracted.  Thus, the overall size of the array is provided to CopyRegion in addition to the sub-region.  EncodeXFB already handles the extraction, so CopyRegion's only use there is to resize the image (and thus no sub-region is provided).