LOTS of refactoring done.
Isolate mempool and OMT into a new class, bndata.
Remove key from the leafentry.
Merge branch 'ft-index/46-refactor' into 46-refactor-staging

Conflicts:
	ft/tests/le-cursor-provdel.cc
	ft/tests/le-cursor-right.cc
	ft/tests/le-cursor-walk.cc