lib/tree/node: do node_{ap,pre}pend_multiple with node_xfer_multiple
lib/tree/node: add prototype for node_{ap,pre}pend_multiple in node.h
lib/tree/node: accept last index in node_shift_*
lib/tree/node: set cnt properly; get leaf from source node
lib/tree/check: update for changed node code
git ignore: add docgen/ pattern
all: make everything compile