Add cancellation support to content-aware rescale

Important, as it can take awhile!
Fix live translation updates for various toolbars

Trickier than I expected, as statements like "Form.Caption = [String]"
cause toolbars to lose all positioning and border data.

Note also that tooltips are not restored by this function.  Rather than
go through the very complicated work of changing this, I will be adding
a simple message box post-language-change warning the user to restart
for full translation updates.
Display warning after live translation change

I hate modal dialog boxes and/or "bandaid-style" fixes like this, but
the work required to live-update tooltips and other minor text is
extraordinary... so I'm calling this the lesser of two evils.

Also, language should only ever be changed once (from the default to the
user's choice) so I'm not too concerned about the workflow impact of
this dialog box.