Delete Xcode project file

This doesn’t work with latest versions of Xcode. No reason in spending time updating the project file for a project as simple as this.
Move sources and resources to subfolders
Add ‘target’ file for TextMate’s build system
Fix warnings (64 bit / “modern” SDK)

Mainly converting source to use CGFloat and NSUInteger.
Don’t deselect files when TM_SELECTED_FILES is set

We assume that when this variable is set, the command calling us are only giving us the set of (user) selected files, and it would be counterproductive to not have all those included in the commit (by default).