matdbg is now linked into the Filament Engine in debug config (allowing
live inspection of GLSL / SPIRV) and into the matinfo tool (to support
the --web-server option).
In both cases, the library spins up a small web server that listens to
http://localhost:8080. You can run any Filament app and attach to it.
The web client caches all material information. This allows the user to
close an atttached Filament app, and the web app will continue to
function properly (useful for crash diagnosis). Moreover the user can
launch a second Filament app and the web client will add its materials
to the existing list (useful when comparing two Filament apps).
For now this only supports inspection, not editing. Some of the material
info such as required attributes is not yet displayed but this will be
easy to flesh out in a subsequent PR.
