Private role attributes are now visible in class

Thanks to extensive support by jnthn++.  Unfortunately, getting this to work
for private *native* role attributes, proved to be needing to go deeper into
the rabbit hole.  Which will be for another day.
Only need $/ for the first occurrence of attribute
Fix most of the nasty nqp::get_attr calls

Now that classes can see private role attributes
Implement *Scheduler.cue( :times )
named params are optional by default
Implement (hidden) :SINK attribute on slices

The idea being that te optimizer will add this when it sees a :delete being done
in sink context.
Fix additional dereference, thanks to TimToady++

$ perl6-p -e 'my %h=a=>1,b=>2; say so all %h<a b c>:exists'
False
Put the burden of :SINK on :delete only
fix whatever currying for chain ops

When a WhateverCode gets created from a chain op, it'll be annotated
with its original arguments and when a WhateverCode with a chain op ends
up calling a WhateverCode that also had a chain in it, it will "flatten
out" the arguments of that WhateverCode, creating a proper chain.
fix remaining problems with whatever_curry and chain ops
Merge branch 'chained_whatevercode' into nom

This fixes WhateverCode generation when chain ops are involved.
A few changelog entries for this month
two more changelog entries
split December and January releases between masak++ and me
run the QRegex optimizer from rakudo's optimizer.
bump NQP revision to get the regex optimizer.
put regex optimizer changes in the changelog
implement m:/\Q\E/
give non-parrot's CallFrame the $.level, too.
copypasto, spotted by moritz++