* Fix memory leak related to aliasrun(). Precmd, Cwdcmd etc. leak memory.

* Fix migrate -site $$... Seems to hang... (aix370)

* Fix history in loops.

* Fix loops so that they work inside aliases.

* Fix variable substitutions so that can behave recursively; i.e. I want
  to be able to say echo $foo:t:e

* New idea.
	Lots of people seem to like the idea to be able to do sed type
	operations on shell variables. Maybe we can extend the syntax
	of the variable editing to understand string operations.
	So I would like to be able to use:
	> set a="this is a STRING"
	> echo $a:[3-]
	is is a STRING
	> echo $a:[#]
	16
	> echo $a:[6-7]
	is
	> echo $a:[-2]
	ng
	> echo $a:[-20]
	Subscript out of bounds.
	> echo $a:[2-20]
	Subscript out of bounds.
	> echo $a:l
	this is a string
	> echo $a:u
	THIS IS A STRING
	> echo $a:[1-1]:u$a:[2-].
	This is a string.

* Fix pipelines that contain builtins so that they behave correctly.
  I tried to fix that (most of the code is in sh.sem.c, but it works
  only for non POSIX machines cause otherwise the setpgid() I added
  fails).

* Fix the correct code... How to do that involves A.I....