Added missing BMessage::{Get|Set}String() methods.

* Forgot to add those before accidentally.

headers/os/app/Message.h

@@ -475,6 +475,9 @@ public:
 			status_t			SetInt64(const char* name, int64 value);
 			status_t			SetUInt64(const char* name, uint64 value);
 			status_t			SetPointer(const char* name, const void* value);
+			status_t			SetString(const char* name, const char* string);
+			status_t			SetString(const char* name,
+									const BString& string);
 			status_t			SetFloat(const char* name, float value);
 			status_t			SetDouble(const char* name, double value);
 			status_t			SetAlignment(const char* name,

src/kits/app/Message.cpp

@@ -2564,6 +2564,7 @@ DEFINE_SET_GET_FUNCTIONS(uint64, UInt64, B_UINT64_TYPE);
 DEFINE_SET_GET_FUNCTIONS(bool, Bool, B_BOOL_TYPE);
 DEFINE_SET_GET_FUNCTIONS(float, Float, B_FLOAT_TYPE);
 DEFINE_SET_GET_FUNCTIONS(double, Double, B_DOUBLE_TYPE);
+DEFINE_SET_GET_FUNCTIONS(const char *, String, B_STRING_TYPE);
 
 #undef DEFINE_SET_GET_FUNCTION
 
@@ -3135,6 +3136,13 @@ BMessage::HasFlat(const char *name, int32 index, const BFlattenable *object)
 }
 
 
+status_t
+BMessage::SetString(const char *name, const BString& value)
+{
+	return SetData(name, B_STRING_TYPE, value.String(), value.Length() + 1);
+}
+
+
 status_t
 BMessage::SetData(const char* name, type_code type, const void* data,
 	ssize_t numBytes)