output record position as returned by target
* the position is returned as an attribute of each <location> hit
added cmd "ingested"
removed trailing whitespace
make ingest mode optional, as cmdline arg `-i`
Also, `-ii` turns on "hardcore ingest mode", where records are not merged etc (`show` and `termlist` return nothing). Saves CPU & memory where this pz2 functionality is not needed. `init`, `search` and `bytarget` are not affected.

With a single `-i`, normal pz2 commands all works as usual, plus `ingest` cmd is added. Without any `-i`, `ingest` cmd does nothing (always returns zero records).
reversed ingested list ordering
* for more efficient processing -- the most common scenario is asking for new records at the end, which is more efficient now
* ingested records from <start, end) are now returned in reverse order: (end, start>. We only need the new records as a set, so ordering doesn't matter.
changed ingested params from <start, end) to <start, start+num)