Get rid of numba import

Not used in general use, and numba is not supported on the cluster
Fix the vocab non-zero minimum to 1E-10

This give much better results. Roughly equivalent to a prior with
symmetric param set to 0.1
Merge branch 'master' of https://github.com/budgefeeney/sidetopics

Conflicts:
	src/model/lda_vb.py
Eliminate debug prints and dead code
Ensure we respect dtype in constantArray in LDA/*
Work around absence of isnan on cluster Cython
More constantArray fixes