Use size_t for lengths in stream objects

Provides safety against them accidentally becoming negative because
of bugs in the calculations.

Also does the same to CharArray and friends as they were strongly
connection to the stream objects.

common/rdr/TLSInStream.h

@@ -36,17 +36,17 @@ namespace rdr {
     TLSInStream(InStream* in, gnutls_session_t session);
     virtual ~TLSInStream();
 
-    int pos();
+    size_t pos();
 
   private:
-    int overrun(int itemSize, int nItems, bool wait);
-    int readTLS(U8* buf, int len, bool wait);
+    size_t overrun(size_t itemSize, size_t nItems, bool wait);
+    size_t readTLS(U8* buf, size_t len, bool wait);
     static ssize_t pull(gnutls_transport_ptr_t str, void* data, size_t size);
 
     gnutls_session_t session;
     InStream* in;
-    int bufSize;
-    int offset;
+    size_t bufSize;
+    size_t offset;
     U8* start;
   };
 };