Revert "Merge branch 'enhanced_device' of github.com:john30/ebusd"

This reverts commit aaccb15a9b, reversing
changes made to edfe09a383.

src/lib/ebus/symbol.h

@@ -72,19 +72,19 @@ using std::vector;
 typedef unsigned char symbol_t;
 
 /** escape symbol, either followed by 0x00 for the value 0xA9, or 0x01 for the value 0xAA. */
-#define ESC ((symbol_t)0xA9)
+#define ESC 0xA9
 
 /** synchronization symbol. */
-#define SYN ((symbol_t)0xAA)
+#define SYN 0xAA
 
 /** positive acknowledge symbol. */
-#define ACK ((symbol_t)0x00)
+#define ACK 0x00
 
 /** negative acknowledge symbol. */
-#define NAK ((symbol_t)0xFF)
+#define NAK 0xFF
 
 /** the broadcast destination address. */
-#define BROADCAST ((symbol_t)0xFE)
+#define BROADCAST 0xFE
 
 /**
  * Parse an unsigned int value.