Major update to EM4x70 support:

1. Rework how communications with tag occur.
    a. bitstream to be sent to the tag is now fully pre-generated.
    b. bits sent and received are logged with start / end times.

2. Support built-in `hw dbg` for controlling verbosity of debug output

The new bitstream generation and logging has exposed a surprising legacy behavior ... each of the command that sent additional data (beyond the command) were:
* inserting an extra RM zero bit
* force-enabling command parity is used

This was not expected.  However, this PR maintains the behavior of the existing code.

TODO: Root-cause why the third RM bit is needed.  Fix code to remove that hack.

TODO: change the arm/client interface to ONLY use arrays of bytes, with well-defined content endianness, to avoid this problem.

armsrc/em4x70.h

@@ -19,12 +19,11 @@
 #ifndef EM4x70_H
 #define EM4x70_H
 
+#include <stdint.h>
+#include <stdbool.h>
+#include <assert.h>
 #include "../include/em4x70.h"
 
-typedef struct {
-    uint8_t data[32];
-} em4x70_tag_t;
-
 typedef enum {
     RISING_EDGE,
     FALLING_EDGE