This formats all copyright comments according to SPDX formatting guidelines.
Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
This is an analog of BitSet from Dolphin that was introduced to allow
iterating over a set of bits. Given it's currently unused, and given
that std::bitset exists, we can remove this. If it's ever needed in the
future it can be brought back.
Morph