First whack at (;;) and [;;] producing LoL

It works for those constructs, but breaks other stuff subtly.
add SEQ(a; b) circumfix to do what (a; b) did

The $() construct also assumes sequence semantics, since it only wants one value.
These are roughly equivalent except where nqp macros need SEQ() to compile down
to the bare sequence of statements without any addition coercion.  $() also works
for code that wants to be backward compatible to pre-lolly days, like spec tests.
Don't loop on 0-art infix:<Z>
unbreak zen slices
keep () from disappearing prematurely

also fix tabs
Merge branch 'nom' into lolly

Conflicts:
	src/core/LoL.pm
trap old (;) usages unless LOLLY set
Merge branch 'nom' into lolly

Just to make sure we're in sync.