New rule function "backtrack" & reflect #

[atom]

Lets say you have "m1" for memorize, "m2" for append buffer and "m3" for prepend buffer.

The rule: m1 r [ m3

Should do the same as "b".

m1 remembers the original buffer "p@ssW0rd".

r reverses it, so it becomes "dr0Wss@p"

[ removes the first character, so it becomes "r0Wss@p"

m3 prepends the saved buffer, so it becomes p@ssW0rdr0Wss@p

But there should be a lot of other scenarios where this could be used