temp stuff for tracing Comet
item tags by reference - @x: @y - 'add-more' like 'More' on lists, 'with-more' like 'with' on lists
allow colons inside tags, obviously
bits
each - like with-more but doesn't use existing
with-more can take a list of rhs items
with-more and each use @.. for current list reference (broken for singles though)
fix broken single element reference case
@.. in cars; new look-up table mapping source result items to derived items
@.. on with-more rhs list
eval lhs and rhs in the copyMoreList code
select .. else