Beta quality drop of Objective C Support.

- Add more to the ObjC dir readme.
- Merge the ExtensionField and ExtensionDescriptor to reduce overhead.
- Fix an initialization race.
- Clean up the Xcode schemes.
- Remove the class/enum filter.
- Remove some forced inline that were bloating things without proof of performance wins.
- Rename some internal types to avoid conflicts with the well know types protos.
- Drop the use of ApplyFunctions to the compiler/optimizer can do what it wants.
- Better document some possible future improvements.
- Add missing support for parsing repeated primitive fields in packed or unpacked forms.
- Improve -hash.
- Add *Count for repeated and map<> fields to avoid auto create when checking for them being set.
diff --git a/objectivec/GPBWireFormat.m b/objectivec/GPBWireFormat.m
index 7435221..193235d 100644
--- a/objectivec/GPBWireFormat.m
+++ b/objectivec/GPBWireFormat.m
@@ -49,30 +49,30 @@
   return GPBLogicalRightShift32(tag, GPBWireFormatTagTypeBits);
 }
 
-GPBWireFormat GPBWireFormatForType(GPBType type, BOOL isPacked) {
+GPBWireFormat GPBWireFormatForType(GPBDataType type, BOOL isPacked) {
   if (isPacked) {
     return GPBWireFormatLengthDelimited;
   }
 
-  static const GPBWireFormat format[GPBTypeCount] = {
-      GPBWireFormatVarint,           // GPBTypeBool
-      GPBWireFormatFixed32,          // GPBTypeFixed32
-      GPBWireFormatFixed32,          // GPBTypeSFixed32
-      GPBWireFormatFixed32,          // GPBTypeFloat
-      GPBWireFormatFixed64,          // GPBTypeFixed64
-      GPBWireFormatFixed64,          // GPBTypeSFixed64
-      GPBWireFormatFixed64,          // GPBTypeDouble
-      GPBWireFormatVarint,           // GPBTypeInt32
-      GPBWireFormatVarint,           // GPBTypeInt64
-      GPBWireFormatVarint,           // GPBTypeSInt32
-      GPBWireFormatVarint,           // GPBTypeSInt64
-      GPBWireFormatVarint,           // GPBTypeUInt32
-      GPBWireFormatVarint,           // GPBTypeUInt64
-      GPBWireFormatLengthDelimited,  // GPBTypeBytes
-      GPBWireFormatLengthDelimited,  // GPBTypeString
-      GPBWireFormatLengthDelimited,  // GPBTypeMessage
-      GPBWireFormatStartGroup,       // GPBTypeGroup
-      GPBWireFormatVarint            // GPBTypeEnum
+  static const GPBWireFormat format[GPBDataType_Count] = {
+      GPBWireFormatVarint,           // GPBDataTypeBool
+      GPBWireFormatFixed32,          // GPBDataTypeFixed32
+      GPBWireFormatFixed32,          // GPBDataTypeSFixed32
+      GPBWireFormatFixed32,          // GPBDataTypeFloat
+      GPBWireFormatFixed64,          // GPBDataTypeFixed64
+      GPBWireFormatFixed64,          // GPBDataTypeSFixed64
+      GPBWireFormatFixed64,          // GPBDataTypeDouble
+      GPBWireFormatVarint,           // GPBDataTypeInt32
+      GPBWireFormatVarint,           // GPBDataTypeInt64
+      GPBWireFormatVarint,           // GPBDataTypeSInt32
+      GPBWireFormatVarint,           // GPBDataTypeSInt64
+      GPBWireFormatVarint,           // GPBDataTypeUInt32
+      GPBWireFormatVarint,           // GPBDataTypeUInt64
+      GPBWireFormatLengthDelimited,  // GPBDataTypeBytes
+      GPBWireFormatLengthDelimited,  // GPBDataTypeString
+      GPBWireFormatLengthDelimited,  // GPBDataTypeMessage
+      GPBWireFormatStartGroup,       // GPBDataTypeGroup
+      GPBWireFormatVarint            // GPBDataTypeEnum
   };
   return format[type];
 }