Mad ramblings about registers

registers.txt

I think the idea I was working with is that a large number of primitives are just
register copies, so I was thinking about introducing <a-">, which is a kind of 
"register copy" operator, making a bunch of primitives redundant.

"&    = current selections

y     = <a-">."
R     = <a-">".
<a-R> = <a-">"<a-_>.
z     = <a-">^&
Z     = <a-">&^
<a-d> = <a-">_.
P     = <a-">"<gt>
<a-P> = <a-">"<a-_><gt>
p     = <a-">"<lt>
<a-p> = <a-">"<a-_><lt>

<c-s> = <a-">&<c-s>&y
<c-o> = <a-">&<c-o>&y

d.    = ???  _ -> . -> "

"<c-s>y
"<c-o>p
"<c-i>p

* "& becomes the selections register
* <c-s>, <c-o>, <c-i> take a register (default "&)

* all registers become stacks
* allow <c-s>, <c-o>, <c-i>, <c-=> after "
* y/c/d act like "<c-s>y/c/d