This way, zooming, panning etc. gets sped up quite a bit.

1) winwidget.c winwidget.h New function winwidget_update_caption using code in winwindget_render_image. This code was removed from the latter, and replaced with a call to winwidget_update_caption.

2) Image caption is updated after running action when in slideshow mode.
3) Running action in slideshow mode no longer changes the image automatically.

Does not yet work with initial zoom value != 100%

Just in case, and we don't want the compiler to complain about it, do we? ;)