initialize it for full gc if we think it is worth it. This allows for
full gc to run when bringing a basement node up to date.

there may be an abort message waiting to be applied.

in a different order than they began, and blow up a bad assert.

separate the difference between the oldest referenced xid we can use for
implicit promotion vs simple garbage collection.

run full garbage collection when a leafentry has > 1 committed entry.

can iterate over and clean up, which prevents a memory leak when the
fractal tree shared library unloads before all thread-local destructors run

This reverts commit 843f0050.

Should have been on a branch.

This reverts commit 7fa771e0.

Should have been on a branch.

This reverts commit fbd96859.

Should have been on a branch.

This reverts commit d467d3cf.

Should have been on a branch.

the last point we may read the node variable safely.

TOKU_GLOBAL_STATUS

disk bytes written. Need to add a 'double' engine status type, which
apparnetly exists in the union, but not as a type tag.

node and notices that it is over 32mb

This reverts commit b1c1e93d, reversing
changes made to 60be90af.

Instead just keep mempool around a little longer (like pre-refactoring).  This should
reduce large mallocs and remove a memcpy

Refs Tokutek/ft-index#46 Comments, minor renames, reworked bn_data::move_leafentries s.t. splits do not significantly increase memory usage of basement nodes and to be cleaner

now uses dmt iterate_on_range and the dmt builder instead of a for loop