Optimize rightmost inserts and unique checks using a constant rightmost leaf and a heuristic stored in the FT

non-root leaf node in each FT. When the FT detects a rightmost insertion
pattern, it attempts to do inserts and unique checks directly into the
rightmost leaf node, greatly optimizing sequential insert speed.

We will wait until after TokuMX 1.5.0 for these changes

This reverts commit 1927c6dd.

We will wait until after TokuMX 1.5.0 for these changes

This reverts commit b1f4a0aa.

We will wait until after TokuMX 1.5.0 for these changes

This reverts commit 917a23bd.

appropriate headers

also a typo

fixes #249

in each message tree. This removes a sort during deserialization, which
can be expensive when there are many messages and I/O is fast. This
change supports auto-upgrade from older versions.

Support gcc 4.9 in cmake, fix uninitialized value warnings

fixes #230

added checkpoint duration to engine status #219