Passage walls in Survex

[Footleg]

Talking of the passage walls feature, by which I mean the handling of
LRUD data. In all the other programs I have played with, the LRUD data
is associated with a station in a leg, except Survex which associates
it with just a station. This does not make sense to me, as the LRUD
data needs to be expressed in the context of a survey leg to define
the plane of the passage cross section which the LRUD data is measured
against. For example at a station at a 3 way junction you need to know
which pair of legs the LRUD data relates to. So I would propose
supporting LRUD data attached to a leg. By default take it to be for
the first station in the leg, but allow an option to specify it for
the second station in the leg.

e.g.
;From   To   Tape   Compass   Clino   L   R   U   D  stn
1          2     5.34    234           -6       0.3 0.4 1.4 0.3
;The LRUD data is taken to be for stn 1
2          3     4.62    246           -2       0.2 0.2 1.3 0.4   3
;The LRUD data is taken to be for stn 3 (specified)