Accelerators in the titles of diaElemTimeStamp shown as "&", don't work

[eumagga0x2a]

Time selection dialogs like in the "Black", "Fade to black" and "Fade" plugins which use diaElemTimeStamp show an ampersand "&" instead of transforming an underscore in the title into an accelerator. Methinks this were a recent regression.

[eumagga0x2a]

Fixed by [Qt] Fix & in timestamp widget, thx.