ObjFW  Check-in [49f84877bf]

Legend:
 * Changes of existing features or bugfixes.
 + New features.

ObjFW 0.6 -> ObjFW 0.7, 27.10.2012
 Again, the differences are more than in any release before, thus listing them
 all would be too much. The major differences are:
 + ObjFW now comes with its own runtime, which greatly increases performance
   compared to the GNU runtime and is even faster than the Apple runtime
   (using Clang >= 3.2 is recommended, but not necessary).
 * Support for the GNU runtime has been dropped.
 + New, much faster autorelease pool implementation (now inside the runtime).
 + Support for Automatic Reference Counting (requires Clang >= 3.2).
 + Forwarding has been implemented.
 + Asynchronous stream handling.
 + New classes: OFThreadPool, OFRecursiveMutex, OFSortedList, OFTimer, OFRunLoop
 + New protocols: OFLocking, OFTLSSocket
 * Lots of API changes to make APIs more future-proof.
 + Support for the new Objective-C literals.
 * OFHTTPRequest now implements HTTP/1.1.
 * OFObject's memory handling has been improved, leading to better performance.
 * Strings are allocated faster now.
 + Support for JSON5.
 * All private methods use the prefix OF_ now instead of _, making it possible
   to use the _ prefix in applications.
 * Most ObjC compiler feature checks are not part of configure anymore, making
   it possible to use the same installation with different compilers.

ObjFW 0.5.4 -> ObjFW 0.6, 27.02.2012
 The differences between 0.5.4 and 0.6 are too big to list them all. However,
 the major new features are:
 * OFString, OFArray, OFDictionary, OFSet and OFCountedSet are now class
   clusters.
 + Serialization and deserialization of objects into/from XML and JSON.
 + New class OFIntrospection for introspecting classes.