a "non-computational" update() 10 times a second.  This basically blits
the sky pixmap onto the window and draws the infoboxes.  We now only call
update() if the LT/UT/ST time values have changed (so, roughly 1-2 times
per second).

Also, removed hard-coded restriction on width of timespinbox widget.

svn path=/trunk/kdeedu/kstars/; revision=183943