Ninjas can now phase jaunt.

Adds Phase Jaunt for a cost of 250 energy, compared to Phase Shift which costs 400E.
Randomly jumps the ninja 5-9 tiles straight ahead. Does not harm any creature in the way.
Adds cool-down to Phase Shift.

Cell use is now redacted directly in the ninjacost() proc.
Some cleanup of ninja verb-add/removal.

Based on #6311.