Broken buggy topic prior update

Fits the algorithm as described, but it makes the bound worse. The
likelihood apparently improves, but it’s still worse than not doing any
prior update at all.
Fixed bugs in prior update
Remove weird unicode space chars

Not sure why MacOS keeps introducing these…
Split topic inference into a separate function

This is so we can write a general query function without too much copy
and paste.

Also toyed with a random init instead of uniform every time we estimate
topics - turns out the bound no longer increases monotonically if we do
this?!
Re-enabled the convergence test in LDA/VB
Print model prior after training.

However it seems to be getting lost
Syntax error in LDA/VB
Add a f64 LDA/VB query function