Make FindFix work, kinda sorta, in Xcode 5.

Issues (purely cosmetic as far as I can tell):

- Pressing Cmd+F with find already open puts replace widget at the
  bottom of the view (presumably the calling code uses addSubview);
- Find bar layout is a proper mess;
- Show Find Options… menu option is enabled, but does nothing.
Improve Xcode 5 find bar appearance when FindFix is active.
Fix incorrect position of replace text widget when finder mode changes.
Fix dodgy comparison - though I’m not sure it’s THAT much better now.
Remove find options menu item.
Remove some unused code.
Reinstate Xcode 4.6 compatibility.
Replace calls to undeclared selectors with calls to objc_msgSend.

Cut down on warning spam.
Add version 0 of find text auto populate.

This to fix issue #17.
Turn Auto Populate button into a menu bar option.

Hopefully it now makes a bit more sense that the option doesn’t take
effect immediately…
Fix Auto Populate option for Xcode 4.