Switch to stdbool.h

- Add `#include <stdbool.h> to all files previously using the
   `TRUE`/`FALSE` macros
 - Replace all instances of `TRUE`/`FALSE` with `true`/`false`,
   respectively
 - Definitions of `TRUE`/`FALSE` macros retained in wiringPi.h for compatibility.

examples/PiGlow/piGlow1.c

@@ -25,6 +25,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <poll.h>
 
 #include <wiringPi.h>
@@ -32,11 +33,6 @@
 
 #define	PIGLOW_BASE	533
 
-#ifndef	TRUE
-#  define TRUE  (1==1)
-#  define FALSE (!TRUE)
-#endif
-
 
 /*
  * keypressed: clearKeypressed: