* Update fixtures to 0.8.3
* v0.8.1 tests use new test path
* LFS caching: handle multiple versions of json_tests
* Enable paths > 260 characters in appveyor
* Appveyor: use git clone core.longpaths + the env variable at startup
* improve process_lfs.sh and cleanup submodules
* handle LFS fixtures for the test suite
* test_fixture_ssz_static.nim: allow the tests to fail properly
- switch to a debug build for the failing tests
* try -d:debug