Intercept the same all along the flight path

Intercept the same all along the flight path

In each sector, any country owning the sector, a surface ship or a
land unit gets to intercept.

Before, only the sector owner got to intercept, except for the target
sector.  There, any country owning surface ships or land units got to
intercept in addition to the sector owner.  Thus, a sector owner with
surface ships or land units there got to intercept twice.

Info Intercept claimed you get to intercept once for ships and once
again for land units, which was wrong since 4.0.9.

Info bomb suggested that flak fires only in the target sector, which
was wrong since 4.2.8.  Drop that.