Implement Python 3 bindings, so wasm3 can be easily used from Python.

This is discussed a bit more in #456.

Currently, to copy off files from the fs is to 1. mount, 2. chattr, 3. chmod/chown, 4. copy files off. However, this is destructive to the fs (since it changes permissions/users). Instead, there should be a less invasive way to copy off files that doesn't mess with the underlying fs so that people can copy the fs and use it somewhere else.

I just found https://github.com/dalance/svlint and would be interested how it copes with the ibex code base.

Minimal test case:

jal x1 l1
l1:
nop

This assembles to:

 Address    Code        Basic                     Source

0x00000000  0x004000ef  jal x1,0x00000002     1    jal x1 l1
0x00000004  0x00000013  addi x0,x0,0x00000000 3    nop

(This is compact .text at 0, but it doesn't matter since JAL is relative)

However, according to [the spec](https://riscv.org//