2008-08-13	Timo Bingmann
	* btree.h: Replacing many / 2 integer divisions with >> 1 as
	suggested by received e-mails. This may or may not improve
	speed. I personally doubt it, because modern compilers should
	optimize these simple instructions.

2008-08-01	Timo Bingmann
	* btree.h: Completely reworked reverse_iterator classes. Now they
	are real implementations and do not use STL magic. Both
	reverse_iterator and const_reverse_iterator should work as
	expected now. Added two large test cases for iterators. Also
	enabling public Default-Constructor on iterators.
	
2008-08-01	Timo Bingmann
	* btree.h: Fixing up a memory access bug which happens in
	leaf->slotkey[leaf->slotuse - 1] if leaf-slotuse == 0. This doesnt
	have any other bad effect, because the case only occurs when leaf
	== root and thus the btree_update_lastkey message is never really
	processed. However it still is a bad-memory access.

2008-01-25	Timo Bingmann
	* btree.h: Fixed a valgrind-detected bug based on a new test case
	received via email. During the find() function find_lower() is
	called and returns the slot number with the smallest or equal
	key. However if the queried key is larger than all keys in a leaf
	node or in the whole tree, find_lower() returns a slot number past
	the last valid key slot. Comparison of this invalid slot with the
	queried key then yields an uninitialized memory error in valgrind.

2007-05-12	Timo Bingmann
	* btree.h: Fixed segfault in print() because of non-existing root.
		   Fixed segfault in end() when the tree is totally empty.
		   Added BTREE_FRIENDS macro so that wxBTreeDemo can
		   access private members.
		   Changing print function to output to a user-given
		   std::ostream