ODE loop modifier (was: make -V default behavior change)

[Edgar Fuß <ef%math.uni-bonn.de@localhost>]

> The @.c.@ loop syntax should really not be allowed
I disaggree. First, I find it more readable to write
	cidrs.trusted+= ${nets4.trusted:@.net.@${NETCIDR4.${.net.}}@}
than the corresponding .for loop.
Second, there are things you simply can't express (or so I think) with 
.for loops, like constructing a single shell command from a list.

> the behavior of ordinary for loops is confusing enough.
Not since you fixed the lopp variable expansion, I think.

I'm still considering KRE's ``one thing at a time'' argument, though.