PageControl: Implements standardised Ctrl+TAB and Ctrl+Shift+TAB shortcuts.
PageControl: Implements standardised Ctrl+TAB and Ctrl+Shift+TAB shortcuts.

The old shortcuts were some unique fpGUI combination which confused
everybody, and didn't work so well anyway. These old ones are now removed.

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI