Change PT update & query parameters

Rather than query_sweeps, specify query_freq, i.e. the number of
subdivision of the full update sweeps.

If update_sweeps is not divisible by query_freq, the true update_sweeps
will be diminished until it is.

For example:

update_sweeps = 100
query_freq = 8

results in a query every 12 sweeps and an update attempt every 96.