Add ToggleFullscreen to QKeySequence

A ToggleFullscreen member should be added to the QKeySequence enum. F11 is the common standard for entering fullscreen in Windows/GNOME/KDE.

For OS X, we have the following (sampled from the apps I happen to have on my machine):

Cmd+Ctrl+F:
Mail
iCal
Address Book
iTunes
Safari
Xcode
DVD Player
iMovie
iPhoto
Photo Booth
Preview
QuickTime Player
Terminal is strangely Cmd+Option+F... looks like Apple wasn't consistent on EVERY app
Skype

Cmd+Shift+F:
Mozilla Firefox
Google Chrome
Opera
FaceTime
Kindle
Instruments (/Developer/Applications)
(Adobe Reader, Qt Creator and TextWrangler map this to a find or search function)

Odd Ones Out:
NetBeans = Ctrl+Shift+Enter
OpenOffice.org/LibreOffice = Cmd+Shift+J
Microsoft Remote Desktop = Cmd+2
VLC Media Player = Cmd+F
Adobe Reader = Cmd+L

So, Cmd+Ctrl+F appears to be IS the "official" fullscreen shortcut according to Xcode / Interface Builder, although several major apps (including Apple's own FaceTime) use Ctrl+Shift+F and Terminal very strangely uses Cmd+Option+F. However most of those using Ctrl+Shift+F are web browsers.

I propose that we add ToggleFullscreen to QKeySequence with Cmd+Ctrl+F as the assignment for Mac OS X, and F11 for Windows, GNOME and KDE.

Also see: http://en.wikipedia.org/wiki/Table_of_keyboard_shortcuts