adding hardwaret timer and fixing PWM pins errors

[TianpeiLee]

You can set pwmout like this :

 analogWriteFrequency(16000);                //you can set output frequency
 pinMode(PWM_OUT_5, OUTPUT);          //config pins
 analogWrite(PWM_OUT_5,2048);           // config duty, default 12bit

or you can config timer like this:

HardwareTimer *HardTim = new HardwareTimer(TIM2);
HardTim->setOverflow(1000, HERTZ_FORMAT); // 1000 Hz
HardTim->attachInterrupt(Update_IT_callback);
HardTim->resume();

void Update_IT_callback(void)
{
digitalWrite(LED_PIN, !digitalRead(LED_PIN));
}