Alpha release of FBX2glTF v0.9.6

It has been a full sixteen months since the FBX2glTF 0.9.5 saw the light. The code has changed quite a bit: FBX2glTF 0.9.6 aggregates 122 commits of varying magnitude, summarised below.

There are some enhancements, many many bug fixes, and some dramatic refactoring. The newness is exciting, but it's also cause for pause: not all the new code has seen much use, and some of it likely needs further iteration. Furthermore, there are many outstanding issues as well as pending PRs that need attending. All this means we should should expect either a 0.9.6b or a 0.9.7 before long.

Changes:

• 3ds Max's "Physical Material" is now detected and parsed as a PBR material.
• We now export FBX lights using the KHR_lights_punctual extension.
• Better cross-platform handling of non-ASCII files and paths (though the SDK itself remains a source of truculence.)
• User-defined properties on FBX nodes as well as materials are now transcribed into the associated glTF extras sections.
• The time extents of animation clips are no longer sourced from the deprecated "animation take" logic; instead we introspect on the actual keys.
• Draco compression settings are now far more configurable on the command line.
• Dozens of nameless edge-case crashes have been fixed, platform-dependent compiler issues worked out, and typos corrected.
• Multiple FBX entities that were previously distinguished by name now have more sophisticated identifying keys.
• The tool now knows what release version it is, as opposed to the meaningless "2.0" it previously reported.
• Blendshape channel names are now exported as the associated glTF accessor's name.
• The codebase itself has been broken up and reorganised quite a bit, and made consistent through the glory of clang-format. There's more to do here, for days when deckchair rearrangement appeals.
• There's now a Dockerfile available for the various situations in which that's useful.
• We've embraced conan.io to speed up our builds. This means many of our third-party dependencies are now downloaded in precompiled binary form.
• We now build (exclusively) against FBX SDK version 2019.2.
• Smoke tests and automated release builds now run via Travis and AppVeyor.