* Uses new repo, which builds all dependencies as static libraries in
Xcode project to reduce CLI dancing.
* Removes AppKit dependency, so that iOS support can be easily added.
This implementation is smaller and less complex, as the branches
for processing parameterGroups have been simplified.
The logic in Config.swift for processing ParameterGroups has been
simplified and removed concerns related to validating groups, which
now lies with SlangShader