concept code for dynamic block size.  works well with 2T load on 32G machine.  needs work for production.
safety checkin:  code compiles but zero testing ... and code incomplete.
code complete ... testing starts
clear warning message
Merge branch 'mv-dynamic-block-size' of github.com:basho/leveldb into mv-dynamic-block-size
fix two warnings
tunings based upon first 3 big tests
add current_block_size_ member variable to use with non-critical point compactions.  address unrelated concern about file numbers and threads ... looks unnecessary, but safer
add some timers to smooth both step up and step down
add global variable to override fadvise usage.  add 2.0 fix to bug in ShouldStopBefore().
Address code review comments.
Merge pull request #111 from basho/mv-dynamic-block-size

Mv dynamic block size
merge 1.4.4 mv-fadvise-control to 2.0
Merge pull request #113 from basho/mv-fadvise-control-2.0

Mv fadvise control 2.0
Add option for iterator_refresh, which is currently implemented in eleveldb
Merge pull request #114 from basho/mv-iterator-refresh

mv-iterator-refresh (part 2)
put a cast within the sqrt() call to help Solaris 13 compile.
reduce thread counts in general compaction, .log, and level-0 thread pools.
add logic to keep all level 0 and 1 files in page cache
reduce compaction threads to level that helped 2 drive stripe array