Add ArrayUtils test: lengthArray
Add ArrayUtils test: condensedLengthArray

This one uncovered a bug.
Fix condensedLengthArray checking that current element is zero

The loop is supposed to check that all places skipped by a nonzero are
zeroes, but it ended up checking the first element (the nonzero) as
well. Fixed by checking i against initI before the >0 check (the <0
check remains, as negatives are unacceptable under any circumstance).
condensedLengthArray: Fix failure to check last skipped element
condensedLengthArray: increment i instead of conditional check

If we're skipping the first skipped element and incrementing i anyway,
why don't we spare the loop the trouble and increment i before it even
starts?