lib: avl: Add tree cleanup functions

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
lib: avl: Fix rotation parent bug

Rotations didn't fix all the parental references. Now they do.

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
lib: avl: Add list like functionality

In order to provide fast next and previous pointers, list like
functions have been added.

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
fs: pipe: Add comments and data buffer code

Basically made the start of the fifo part of the pipe. Administration
is now complete, let's get cracking with the data.

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>
Merge remote-tracking branch 'avl/master' into pipe

Add data cleanup functions to the tree, in order to flush the pipe

Signed-off-by: Bart Kuivenhoven <bemkuivenhoven@gmail.com>

Conflicts:
	src/lib/avl/tree.c