`inhibit-mark-movement'

[Paul Pogonyshev]

In Transient Mark mode commands that use `inhibit-mark-movement'
variable have one more desirable (to me, at least) behaviour:

    When in transient mark mode and the mark is active, don't
    move it.  If the mark is inactive, do move it.

The latter is useful because it enable popping to the position
where command was invoked.

In other words, I'd like these two scenarios be possible
simultaneously (in Transient Mark mode):

    1. Select text from point to the end of function: C-SPC C-M-e

    2. Glance at buffer beginning and go back: M-< C-u C-SPC

We could make any non-nil and non-t value activate the descrubed
behaviour.  Will a patch for this be accepted?  Maybe
`inhibit-mark-movement' should also be made customizable?

Paul