Add lines to avoid warning about unused var

When using a template instance in two different ways (for example, different settings struct for differents objects), a lot of lines of warning appear due to some variables being unused. 
Using these lines, those variables are used for doing nothing and the warnings go away.

Author: RobertoHE

src/BLEMIDI_Transport.h

@@ -256,10 +256,10 @@ class BLEMIDI_Transport
         byte headerByte = buffer[lPtr++];
 
         auto timestampHigh = 0x3f & headerByte;
-
+        timestampHigh = timestampHigh; // <-- This line is for avoid Warning message due it is unused
         byte timestampByte = buffer[lPtr++];
         uint16_t timestamp = 0;
-
+        timestamp = timestamp; // <-- This line is for avoid Warning message due it is unused
         bool sysExContinuation = false;
         bool runningStatusContinuation = false;