Tcl-like uplevel considered useful

["Golubev I. N." <gin-nospam at mo dot msk dot ru>]

I got bored by long-lasting non-solving of macro local variables name
clash problem.  I think that this patch might suggest a solution.
Further explanations are in patch itself, since it also patches
documentation.  I am aware that patches with such a general purpose
are `hard to install because they must be studied carefully'.

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patch for source and documentation