Make Triton VM easy to run

[sshine]

It should be easy to run Triton VM. It's not so easy right now, and there aren't instructions.

There are two scenarios:

• Import Triton VM in a Rust project, e.g. for benchmarking. Inclusion in zkp-compiler-shootout is one goal. The success criterion: It should be possible to import triton-vm as a dependency and use one easy to guess constructor for running the VM (*cough* Too many ways to run the VM #150 *cough*) by feeding it a program in the form of a &str and field elements in the form of u64s.
• Run Triton VM as a command-line tool; Andrew Milson's demo of ministark is a good example; basically one sub-command for proving and dumping something into a file (or stdout), and another sub-command for verifying by reading that file (or stdin).

[jan-ferdinand]

• The first point is addressed by the resolution of Too many ways to run the VM #150, updated and improved documentation, and examples.
• The second point is extracted into add command line tool for proof generation & verification #238.