Remove window hints clearing the flag Qt::WindowContextHelpButtonHint,
which is already off by default in Qt 6.

In Qt 5 this flag was set by default for QDialogs, and on Windows put a
? button in the corner of the title bar allowing users to activate Qt's
QWhatsThis help system for a given widget. Since we don't set that text
the ? button was useless and so we hid it manually.

In NandPaths.cpp, the `std::initializer_list<char>` of illegal characters has been turned into a `char[]` (similar to the one in GameList.cpp).

The reverse iteration in ResourcePack.cpp seemed to provide no benefits, and doing without it it seemed to have no ill effects.

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.

This sends arbitrary packets in chunks to be reassembled at the other
end, allowing large data transfers to be speed-limited and interleaved
with other packets being sent. It also enables tracking the progress of
large data transfers.