ReSTART, Sequencing

pr espressif#1665 introduce a problem with ReSTART, when solving this problem I found an interaction between the TxFifo refill, RxFifo empty and CMD[] fill.  during certain sequences a dataqueue command would be skipped, this skipping resulted in a mismatch between the contents of the TxFifo and the i2c command sequence.  The problem manifested as an ACK error. 
In addition to this required bug fix I propose:
* `Wire.begin()` be changed from a `void` to a `bool` this will allow the reset functionality of `Wire.begin()` to be reported.  Currently `Wire.begin()` attempts to reset the i2c Peripheral, but cannot report success/failure.
* `Wire.busy()` be added. this `bool` function returns the hardware status of the bus. This status can be use in multi-master environments for application level interleaving of commands, also in single master environment, it can be used to detect a 'hung' bus.  With the functional change to `Wire.begin()` this allows app level recover of a hung bus.
* `Wire.lastError()` value updated for all errors, previously when interleaving `Wire.endTransmission(false)` and `Wire.readTransmission(false)`, the 128 byte `Wire.write()` buffer was exhausted without generating and error(very exotic). I discovered this error when I created a sequence of directed reads to a EEPROM. Each directed read used 2 bytes of the 128 byte `write()` buffer, so after 64 consecutive ReSTART writes with ReSTART reads, `Wire()`  had no room to record the directed address bytes.  It generated just a NAK check without setting the EEPROMs internal register address.  The succeeding ReSTART read succeeded at incorrect address.
* Changes to the HAL layer:
** added `i2cGetStatus()` which returns the i2c peripheral status word, used to detect bus_busy currently
** added `i2cDebug()` programmatic control of debug buffer output
** changed `i2cAddQueue()` to allow data_only queue element this will allow a i2c transaction to use multiple data pointers.
** removed direct access to DumpInts(), DumpI2c() from app, use i2cDebug() to set trigger points 
 
*

Author: stickbreaker

Diff for: libraries/Wire/src/Wire.h

@@ -30,7 +30,7 @@
 #include "freertos/queue.h"
 #include "Stream.h"
 
-#define STICKBREAKER V0.2.2
+#define STICKBREAKER V1.0.1
 #define I2C_BUFFER_LENGTH 128
 typedef void(*user_onRequest)(void);
 typedef void(*user_onReceive)(uint8_t*, int);
@@ -67,7 +67,7 @@ class TwoWire: public Stream
 public:
     TwoWire(uint8_t bus_num);
     ~TwoWire();
-    void begin(int sda=-1, int scl=-1, uint32_t frequency=0);
+    bool begin(int sda=-1, int scl=-1, uint32_t frequency=0);
 
     void setClock(uint32_t frequency); // change bus clock without initing hardware
     size_t getClock(); // current bus clock rate in hz
@@ -129,15 +129,18 @@ class TwoWire: public Stream
     void onReceive( void (*)(int) );
     void onRequest( void (*)(void) );
 
-    void dumpInts();
-    void dumpI2C();
+    uint32_t setDebugFlags( uint32_t setBits, uint32_t resetBits);
+    bool busy();
 };
 
 extern TwoWire Wire;
 extern TwoWire Wire1;
 
 
 /*
+V1.0.1 02AUG2018 First Fix after release, Correct ReSTART handling, change Debug control, change begin()
+  to a function, this allow reporting if bus cannot be initialized, Wire.begin() can be used to recover
+  a hung bus busy condition.
 V0.2.2 13APR2018 preserve custom SCL,SDA,Frequency when no parameters passed to begin()
 V0.2.1 15MAR2018 Hardware reset, Glitch prevention, adding destructor for second i2c testing
 */