bug#48580: Outline Mode using Phylogenetic Tree Nomenclature

[pietru@caramail.com]

Currently Outline Mode is confusing because (1) commands begin with describing a tree,
then shifts to describe human beings (body, children); and (2) nomenclature such as branches
and leaves challenge the formal nomenclature of evolutionary trees.

There are also problems with the use of leaves and branches.  Formally, "leaves" are
end-nodes with no children; whereas "branches" are the lines connecting the nodes, their
lengths commonly interpreted as time estimates.  Thusly, "branches" effectively describe
the "body", not nodes themselves.

I advise and lay out a system based on a formal Phylogenetic Tree that implement
Show-Hide Options.

Show All (currently: Show All [unchanged])
Show Offsprings (currently: Show Children)
Show Descendants  (currently: Show Branches)
Show Sub-Tree (currently: Show Subtree [unchanged])
Show Common Level (currently: Hide Sublevels)

Hide Sub-Branches (currently: Hide Leaves - meaning Hide Body after heading)
Hide Branches (currently: Hide Body, leaves all headings visible)
Hide Current Branch (currently: Hide Entry - hide body of this heading)
Hide Sub-Tree (currently: Hide Subtree [unchanged])
Hide Other (currently: Hide Other [unchanged])

Regards
Peter