Fixed memory on Wire instance

[gbr1]

Fixing memory cleanup on Wire instance

Summary

The constructor doesn't cleanup memory for a wire instance.

Issues could happen, such as wrong initialization.

This PR fixes/implements the following bugs/features

• Issue on locked/bad allocated i2c on turning on

Example of bad behaviour using a STM32F411 and an APDS9960 sensor:

#include "Arduino_APDS9960.h"

APDS9960 * apds;
TwoWire * wire;

void setup() {
  Serial.begin(115200);

  wire=new TwoWire(PB7,PB8);
  wire->begin();
  apds = new APDS9960(*wire,PC10);
  apds->begin();
}

void loop() {
  if (apds->proximityAvailable()) {
    int value = apds->readProximity();
    Serial.println(value);
  }
}

The bad behaviour is that after turn off and on the board, wire locks.
Note: it works if you go from boot mode to running mode

This pull request solve this issue adding the following line in TwoWire constructors.

memset((void*)&_i2c, 0, sizeof(_i2c));

[gbr1]

cc @facchinm

[fpistm]

Hi @gbr1
Thanks for this PR.
If you can update with the astyle fixed, please.

[fpistm]

LGTM.
Thanks @gbr1