first cut at sink context

compiles the setting, but fails during startup
only sink when --sink command line option is provided
Failure.sink makes the exception blow up
unbreak Hash/Block distinction
work around nqp::can(Junction, $anything) always returning True
Revert "only sink when --sink command line option is provided"

This reverts commit 3f12074d13a51b2602039ece5f95454055e8abd0.
[release] announcement for 2012.11
[release] logges last missing changes
[release] added 2012.11's contributors
[release] moved 2012.11 up
[release] bump NQP revision
[release] bump VERSION
[release] bump NQP revision
[release] bump VERSION
Merge pull request #88 from FROGGS/nom

[release] 2012.11 "Walnut"
typo in codename
Merge pull request #89 from FROGGS/patch-1

typo in codename
sink last statement in main program
sink END phasers
also sink bare blocks