Bisect and binary insert on sorted lists.

Insert items into a list so the list remains sorted.

Functions:
	bisect(list, item)  -->  return index where item would be inserted
	binsert(list, item)  -->  insert item into list, return index where item was inserted

Based on Python's bisect library.
	Python-2.7.3/Lib/bisect.py
	Python-2.7.3/Modules/_bisectmodule.c

Works with both Lua 5.1 and 5.2.

~~benpop~~