Switched to a `make` based build system, bumped version to 9.3RC1.
The build scripts for PostgreSQL and dependencies have become an unmaintainable mess. Everything was stored inside the project file, making diffs totally unreadable. Now building is performed using a makefile. The `make` based workflow has been added as an external target to the Xcode project. As a result, builds should be faster, because dependencies aren't rebuilt as often any more.
Furthermore, this commit also includes an updated dylib linking script, which should be faster.