filamesh requires UV's but some glTF test models, like CesiumMilkTruck,
do not provide UV's on nonlit parts (e.g. the truck windows). This makes
it so that these assets can be converted to filamesh somewhat more
gracefully.
* grouped MeshAssimp arguments into struct
* added snormuv optimization to MeshAssimp and changed snormuv optimization range from [0, 1] to [-1, 1] in filamesh
Note that the WebGL build uses filameshio, but Android does not. Our
Android samples therefore do not yet understand the compressed format.
For web, I measured the before / after:
```
BEFORE: filament.wasm = 505796, suzanne.filamesh = 521476
AFTER: filament.wasm = 510915, suzanne.filamesh = 333489
```
Issue #558
* Minor clean-ups
- fix a couple usage of std::function
- fix a couple usage of std::string
- remove ALIGN_LOOP, which didn't work
- fix a couple explicit/noexcept
- virtual -> override
* Fix spelling typos and other minor clang-tidy