Make advent2012-day04.t a stress test

Takes around 20 sec to run @moar and 1 min @jvm
Also add integration/advent2009-day21.t
Remove unnecessary parentheses in Main.pm
Merge pull request #258 from Nami-Doc/patch-1

Remove unnecessary parentheses in Main.pm
adding integration/advent2012-day09.t
On JVM, CORE.setting now compiles comfortably in 800m heap.
Suppress unused warnings for constants. Remove unused local.
Provisionally add "is cas" trait to $@%

Just so I can mark the variables in tests that need to be marked this way.
Revert "Provisionally add "is cas" trait to $@%"

This reverts commit 3648d3d63e8e8d071c131517da4572c21c27f7da.
Implement IO.read :rw as specced
Merge pull request #262 from Nami-Doc/patch-2

Implement IO.read :rw as specced
#262 fixup - Add :$rw to `open` sub
Merge pull request #263 from Nami-Doc/patch-3

#262 fixup - Add :$rw to `open` sub
use nqp::seekfh on moar and $!PIO.seek on jvm/parrot
Naive implementation of cas()
Slightly less naive implementation of cas()

jnthn++
Update spectest.data
Merge pull request #257 from dwarring/patch-1

spectest.data changes
Add , fix open :rw
Merge pull request #264 from Nami-Doc/fix-open-rw

Add , fix open :rw