cleave v2.0.0-rc.1, litmus v2.0.0-rc.1, stng v1.4.0

The 2.0.0-rc.1 series swaps cleave's file-parsing engine out for filefacts, a standalone library you can use without the rest of cleave. litmus picks up a new JSON schema and ONNX. stng tightens the garbage filter and fixes a stack-string panic.