makeWord is inconsistently defined

Revise definition to be consistent with other usage of byte

teensy3/WProgram.h

 #include "IntervalTimer.h"
 
 uint16_t makeWord(uint16_t w);
-uint16_t makeWord(byte h, byte l);
+unsigned int makeWord(unsigned char h, unsigned char l);
 
 #define word(...) makeWord(__VA_ARGS__)