teach parrot and jvm about zerowidth literals
first draft of a before-assertion simplifier.
NQP RegexOptimizer for before assertions
less debug output
need to factor in both negations.
more dump output for Regex nodes.
remove apparently dangerous literal optimization
QRegex::Optimizer lives in NQPP6QRegex now.
optimize the topmost regex node as well ...
a scan followed by a BOS anchor is useless.
more work on the 'before' subrule.
pre-size the array for labels in alt.
remove futile scan operations in poscaps and subrules.
teach the regex optimizer about LEVEL
Merge branch 'simplify_before'

This gives us a regex optimizer that can inline simple
<?before> and <!before> assertions and also removes some scans
that it knows to be useless, like at the beginning of a subcapture
or right before a beginning-of-string anchor.