Update to Magnum with new MaterialTools and improved glTF import/export

[mosra]

Motivation and Context

About 15k lines of hot new stuff implemented since #1999 two weeks ago:

• Recognizing additional x86 bit manipulation instruction sets needed by bitfield algorithms, which in turn are needed by about everything else from material tools to draw processing in the batch renderer
• New Containers::BitArrayView::count(), setAll() and resetAll() APIs, with x86-specific variants that use some relatively trivial optimizations for significant perf gains
• Silencing various useless & annoying warnings, mostly related to strict aliasing and false positives about uninitialized variables on GCC 10+
• New TestSuite::Compare::String comparator that prints a colored diff if strings don't match (I was waiting five years for this to become a thing, and the effort put into it paid back on the first day of use.)
• Further improvements to Utility::Json for more convenient parsing of arrays of a homogeneous type
• New Color3::fromLinearRgbInt() and toLinearRgbInt() utilities as well as RGBA variants of these
• New Trade::SceneFieldType::Bit and a general ability to efficiently store and retrieve boolean scene fields
• More descriptive error message in case a CUDA device can't be found, to add more context to issues like Platform::WindowlessEglApplication::tryCreateContext(): unable to find EGL device for CUDA device 0 #1829, Platform::WindowlessEglApplication::tryCreateContext(): unable to find EGL device for CUDA device 0 WindowlessContext: Unable to create windowless context #1991, unable to find EGL device for CUDA device 0 #2002
• MaterialTools::filterAttributes() and MaterialTools::merge() for convenient operations on Trade::MaterialData instances
• Minor additions to support add HBAO visual effect that adds soft shadows to corners and crevices #1997:
  • Ability to pass arbitrary views to GL::Framebuffer::mapForDraw()
  • Added GL::Framebuffer::setDefaultSize() to support attachment-less framebuffers
  • A family of GL::Texture::view() APIs for creating textures as views on subranges of other textures
• First-class support for custom trade.MeshAttribute in the Python bindings
• Full Python bindings for trade.SceneData including read & write access to all scene fields of arbitrary data types. The only types missing are strings and booleans/bits, which need the underlying containers exposed first.
• GltfImporter now imports also booleans and arrays of boolean, numeric and string properties in glTF node extras. This means it's niw possible to import Floorplanner scenes without any warnings from the importer and have access to all the extra data such as fp_tags, fp_category and fp_name, as well as access arbitrary other node extras put into the file.
• Support for exporting the KHR_materials_clearcoat extension in GltfSceneConverter
• Exporting also all custom material properties and yet-unrecognized glTF material extensions in GltfSceneConverter -- this means it should be now possible to save a glTF imported via GltfImporter without losing any material info such as advanced PBR properties or transparency / translucency information, such as is the case with Floorplanner object models.
• in progress And finally, a ✨ magic shader flag ✨ to remove all limits related to material and draw count in the batch renderer, in exchange for potentially slower memory access and restricted platform support.

How Has This Been Tested

🚧 The last feature mentioned above has yet to pass through my own CIs, which is why the PR is marked as a draft. Once I'm sure it passes all my tests, I'll unblock the PR.

[0mdc]

Great stuff! Thank you.

[mosra]

Update re the ✨ magic shader flag ✨: I have it confirmed working locally -- no limits hit even with a 3 GB composite file listed below --, @0mdc is now testing it with the Python viewer.

It however still needs some work, testing, documentation polishing (I underestimated a bit, heh), so it probably won't be ready by tomorrow. Feel free to "undraft" and merge the PR if you need anything from it, I can submit the ✨ magic shader flag ✨ separately after.

[johncruyff14]

Cool