* 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
* Try to clean up asset folders for sample apps.
This removes the build step where we copy a subset of assets, and makes
it so that FilamentApp hands out a "root path" for assets. For now this
is determined based on the location of the executable. This allows
developers to launch samples from any CWD.
Closes#11
* Restore asset copy to build.