* Non-integer powers of negative numbers now yield errors instead
of weird results.
* The selected angle units are saved now.
* Various bug fixes and pixmap cosmetics.
* Added option to choose between infinite and four-element stack in RPN mode.
* Added option to disable autorelease of arc and hyp buttons.
* RPN-related options are now grayed out when the algebraic mode is chosen.
* Added shortcut ctrl-q for exit.