GRAPHICS: Fix a typo in a comment

That -> Set
GRAPHICS: "Xoreos" -> "xoreos"

xoreos is always all lowercase.
GRAPHICS: Change punctuation in a warning message

Just a small change to make it more consistent with the others.
DISTS: Change Mac bundle copyright info to "The xoreos Team"

Since there's now more than just clones and me.
DOCS: Change Doxygen author string to "The xoreos Team"
GRAPHICS: Remember the title between window recreations
DISTS: Use our xoreos.icns on Mac OS X
DISTS: Add resources to Windows binaries, including our icon
GRAPHICS: Set the window icon

- On Windows, use the icon resource in the binary
- On Mac OS X, use the icon resource in the binary
- On all other system, use an embedded static icon

TODO:
- On GNU/Linux, use _NET_WM_ICON to gain support for scalable icons
- On GNU/Linux, use XSetWMHints() to gain support for older WM