Replace TRUE/FALSE with C99 true/false throughout.

This commit removes the old #defines of TRUE and FALSE from puzzles.h,
and does a mechanical search-and-replace throughout the code to
replace them with the C99 standard lowercase spellings.

obfusc.c

@@ -37,7 +37,7 @@ int main(int argc, char **argv)
     unsigned char *data;
     int datalen;
     int decode = -1;
-    int doing_opts = TRUE;
+    int doing_opts = true;
 
     while (--argc > 0) {
 	char *p = *++argv;