Wanted to add a proper variant that reads all layers at once into an
Image3D, but that requires the Image APIs to be made less crappy first.
So it's just this for noew because now I badly need it for
Text::DistanceFieldGlyphCacheArrayGL tests.
I just don't see a point in those. PBOs are for when a roundtrip through
a CPU memory would be wasteful, but these utils are mainly for use in
tests. Definitely not for being called several times per frame, because
the temporary framebuffer creation just doesn't make sense. Not sure
what was I thinking in 2016 when I added those, apart from "feature
parity for no practical reason".
Basically mirroring the changes done for Corrade::Compare::*File*,
including storing the filenames as string views to avoid unnecessary
copies (and then paying extra attention to not pass temporaries to them
in its own tests).
Pros:
* faster compile times (#include <tuple> is 13k lines, ugh)
* ability to have NoInit and ZeroInit constructors
* ability to do fuzzy compare
* named members, so we don't have to use mutable std::tie()
Cons:
* ... none?
The old Color[34]::Hsv is still a tuple and the new ColorHsv is
convertible to/from it (and even std::tie() works). These are all
deprecated (along with the <tuple> include).