Refactor vault for minification.

Refactor vault for minification.
To support name mangling, the stringified Vault worker now redefines the names of its own imports based on each class's mangled name. In the same vein, convert functions and constants have been inlined where used in the Vault. Finally, the worker now dynamically imports NodeJS worker threads when instantiated so that it can be excluded from static imports and avoid mangling.