Make it easier to configure Helium compression in test/format, if
any compression style is configured, turn on Helium compression.
Yeah, it's lazy, but that's how I roll.
typo...
Update cache cleaner information for cursor update and remove, not
just insert.
Upgrade to Helium 2.2
Add debugging code for column-store (record number keys).
Don't bother with a final pass to clean out the cache if we didn't migrate
any changes from the cache to the primary, that pass would be holding locks
and it's not likely to help things much.
Change the Helium cleaner algorithm to use the underlying he_stats.size
value (new in Helium 2.2), for the store instead of maintaining our own
statistics (which implies updating a shared cache line).  This is only
lightly tested, it looks to me like we're triggering a deadlock inside
of the Helium library.

Don't update the cache-inuse flag if it's already set, avoid writing a
shared cache line to no purpose.