Support threaded dispatch

[InvalidPathException]

The current version of Rust stable does not provide explicit tail-calls, for this reason this implementation uses a dispatch table for validation and a huge match statement for invocation (direct dispatch). The performance difference is not immediately clear.

Considering that Rust nightly has recently added better TCO support we can conduct an experiment on this later. Before then, some benchmarking to create a baseline is necessary.

[InvalidPathException]

On hold - seems like TCO is still too unstable.