merge trunk
merge trunk: INST_TAILCALL has bug
merge trunk
merge trunk
Generate better code for the common case of subst-ed variables where the
variable is a simple scalar or an array with a simple literal element name.
Better version that can handle simple composite array keys as well. As long as
they are free of command substitutions, we can still safely omit the exception
processor code.
Improved the sequence of instructions issued for [subst] when dealing with
simple variable references.
Merge the [subst] compile improvements with accommodations to parser changes.