ObjFW  Changes To API Review for 1.0

* ✅ `ObjFW/OFUnlockFailedException.h`
* ✅ `ObjFW/OFUnsupportedProtocolException.h`
* ✅ `ObjFW/OFUnsupportedVersionException.h`
* ✅ `ObjFW/OFURL.h`
* ✅ `ObjFW/OFURLHandler.h`
* ✅ `ObjFW/OFUUID.h`
* ✅ `ObjFW/OFValue.h`
* ❌ `ObjFW/OFWindowsRegistryKey.h`
* ✅ `ObjFW/OFWriteFailedException.h`
* ✅ `ObjFW/OFXMLAttribute.h`
* ✅ `ObjFW/OFXMLCDATA.h`
* ✅ `ObjFW/OFXMLCharacters.h`
* ✅ `ObjFW/OFXMLComment.h`
* ✅ `ObjFW/OFXMLElementBuilder.h`
* ✅ `ObjFW/OFXMLElement.h`

* ✅ `ObjFW/platform/PowerPC/OFAtomic.h`
* ✅ `ObjFW/platform/x86/OFAtomic.h`
* ✅ `ObjFWRT/ObjFWRT.h`
* ✅ `ObjFWTLS/ObjFWTLS.h`

Some things still need to be checked on a global level:

* ❌ Includes that are not installed on every OS
* ❌ Classes that already reserve ivars need to be considered to be changed to restricted subclassing
* ❌ All classes either restrict subclassing or reserve ivars
* ❌ All exception throws need to be audited (they're part of the API, too!)
* ❌ OFSerialization is up for consideration to be removed