Fix command abortion after getting player input

Fix command abortion after getting player input

The old code didn't honor command abortion at the following prompts:

* arm third argument

* deliver fourth argument (also simplify)

* fire third argument

* fly and recon prompt for carrier to land on: pln_onewaymission()
  treated abort like empty input, which made planes attempt landing in
  the sector.

* lmine second argument

* order d fourth argument

* power c nat(s) argument

* range second argument

* sail second argument

* shutdown both arguments (first one was broken in commit 84cfd670,
  v4.3.10, second one never worked).

* tend third argument