History for External Method

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An external method is a method that is defined in a file on the 
file system.  Current external methods are Python based.
Thay can also be written via an extension (e.g. C, C++, Fortran ;),
at least in theory.

A major feature of external methods is that they are not
bound by the security system at all. This has ramifications:

- External methods can be written using languages without
  security hooks.

- Authors can avoid thinking and working hard to create
  a consistent security model thoughout the objects system.
  This can be expedient, reasonable and is sometimes necessary.

We are willing to let external methods bypass the security
system because they are not defined throgh the web and, as
a result have a great deal of trust. Perhaps too much.