Snapshot of REGRESSIONS updates since last night

Failures:
* new compilation issue for Sung's memLeaks/promotion (should now be fixed)
* lingering regression for memLeaks/coforall for GASNet only (sungeun)
* pidigits failing on llvm due to enabling that combination for the first time (expected)
* filerator/walk failing on cygwin due to missing /bin/sh (can't reproduce)

Improvements:
* Vass's sync/single by generic regressions fixed (but still lingering on a few platforms due to lag in testing -- moved them down to the appropriate categories for tracking)
* Lydia's case-sensitivity darwin regressions fixed (but still listed on cygwin due to testing lag)
* miniMD fixed on darwin for reasons I don't understand (maybe I misdiagnosed?)

* regexp_channel_test working on cygwin for reasons I don't understand