Don't set SDKROOT on individual targets

The SDKROOT is set at the project level and inherited by all targets. When set
on an individual target you risk getting the SDKROOT out of sync between the
different targets (some of whom depend on eachother, which is Very Bad™).
Don't over-(auto)release window objects

We never retain these objects, and they have a +0 retain-count, so no need to
(auto)release them.
Drop last use of Carbon (for getting modifier key info on launch) in fe-aqua

During launch we check for modifier keys, and if the Option (Alt) key is down
we don't automatically connect to the network. This used to require using the
Carbon GetCurrentKeyModifiers() function, but as of OS X 10.6 NSEvent
provides a +modifierFlags (class) method that gives you the same information
using AppKit.
Reimplement SGFileUtility as XAFileUtil and use modern APIs

 The code in SGFileUtility was using older file APIs or POSIX APIs and
 contained no source code comments. XAFileUtil replaces this code with modern
 APIs, copiously commented, and cleans up client code to be shorter, more
 consistent, and with (somewhat) better error handling (still more to do on
		 that, but this is a start).

 In particular, the native data type for XAFileUtil is now NSURLs rather than
 the NSString/path-based SGFileUtility. Apple is moving in this direction too,
 but they haven't completed the transition: there are still path-based APIs
 with no URL-based counterparts, and several of the URL-based APIs are not
 available in older versions of OS X (i.e. 10.6).
Remove unused SGArray.{h,m}

XCA doesn't use SGArray so just remove it from the project.
Add some source code comments to SGRegex

SGRegex is using the old POSIX-ish regex functions (non-Unicode safe etc.)
and is only used once in the XCA codebase (in AquaPlugins.m:fix_url()).
Make a note of this and a TODO item to phase it out in favor of
NSRegularExpression once we set our Deployment Target to 10.7.
Phase out SGSoundUtility.{h,m} and update the calling code

SGSoundUtility was used only to find sound files and populate the popup menu in
the "Events/Sounds" Preferences, so phase it out and do the search in
XAFileUtil instead. This makes the calling code much nicer as a side-benefit
(loadSounds:, makeSoundMenu:, and getSoundEvents: should probably be merged).
Fix sound utility
Remove unused SGTokenizer.{h,m}
Full screen support

This adds support for the "Full-Screen Experience" (as the developer docs calls it) in XCA, by enabling the relevant toggles on the XIB and adding a menu item. Runtime introspection should simply disable the widget / menu item on Mac OS X 10.6 (but I haven't tested this).
Fix Sound preference.

Fix SoundEvent initializer problem that fails to find index of sound
Fix set <none> is ignored
Add FoundationExtension/cdebug from cocoapod
remove unrequired glib files from project
Remove unuseful build settings for glib
update glib to 2.35.1
separate fake libintl to libintl-alternative
10.7 support
Add downloads
Replace Maintainer with Homepage in About dialog

Closes #92
Merge pull request #93 from logatron/master

Replace Maintainer with Homepage in About dialog