#27 Prevent undo when in direct edit mode ***73

[David Davidson]

When in direct edit mode (i.e. defining the name of a
new element created from a template dropped into the
model), undo is active and applies to previous changes.
It should either be disabled or else apply to the new
element.

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This bug has been transferred from Tersus' internal bug
tracking system.
The original bug number has been appended to the end
of the bug's summary.