Remove pin high for 40us at end of start sequence

This fixes issue 48, using the method suggested there.

Reference: adafruit#48

Author: Perseudonymous

DHT.cpp

@@ -152,8 +152,12 @@ boolean DHT::read(bool force) {
     InterruptLock lock;
 
     // End the start signal by setting data line high for 40 microseconds.
-    digitalWrite(_pin, HIGH);
-    delayMicroseconds(40);
+    //digitalWrite(_pin, HIGH);
+    //delayMicroseconds(40);
+    //WEB: This is an error. DHT tries to pull the line low as soon as it came back to high.
+    // therefore the low-high transition after the start signal "low" needs to be realised by
+    // the pullup resistor only, uC pin must already be in INPUT mode.
+    // Fixes issue 48: https://github.com/adafruit/DHT-sensor-library/issues/48
 
     // Now start reading the data line to get the value from the DHT sensor.
     pinMode(_pin, INPUT_PULLUP);