better style
add one fuctions.
add a test dir.
update for btree.cc
now finished insert and print methods.
new function drop.
add new functiobs.
add drop function. for btree.
fx bugs.
add comment.
ready to merge.
Merge branch 'master' of https://github.com/xiaolongnk/Alglib

Conflicts:
	.gitignore
	btree.cc
new btree.cc, with deleteKey() finished. ready for test.