Major improvements

Serial communications are now MUCH faster!

- The original method induced a 1-second delay after every command; now, after a command is sent, it awaits a response of either “Done” or “Error” so that it can return instantly.

- Now that sending commands involves checking for a “Done” or “Error” response, all configuration methods now return boolean to indicate whether the change was successful.

- Reading presence status via serial is now almost as fast as `digitalRead()`

New methods:

- `configBegin()` and `configEnd()` allow you to make multiple configuration changes with only a single call to `stop()`, `saveConfig()` and `start()`

- `setTriggerLatency()` allows you to configure delays on confirmation (amount of time that continuous presence activity must be detected before asserting a presence state) and disappearance (amount of time that must not contain any presence activity before deasserting a presence state).

- `begin()` doesn’t currently do anything, but reserved for future use.

Removed methods related to auto-start since there’s not a straightforward way to determine whether the sensor is running.  Factory default is for the sensor to automatically start on power-up, so it’s safer to operate around that assumption.  I may restore these methods at a later date, especially if I decide on what `begin()` will do.

examples/Basic-DigitalTrigger/Basic-DigitalTrigger.ino

@@ -4,7 +4,8 @@
  * This is a basic example of how to instantiate a DFR_Radar object using
  * the second UART available on most Arduino boards.  This example is almost
  * identical to the Basic.ino, except this one uses a digital input to check
- * for presence triggering instead of querying over serial -- much faster!
+ * for presence triggering instead of querying over serial, which could be
+ * somewhat faster.
  *
  * The detection area and sensitivity are set quite low to make it easier
  * to test the unit right in front of you (too high and it'll just stay

examples/Basic-SoftwareSerial/Basic-SoftwareSerial.ino

@@ -73,10 +73,7 @@ void loop()
    * be missed.
    */
 
-  // Query the presence detection status -- this is
-  // kind of slow since it communicates via serial.
-  // This can slow your loop down up to 100ms per
-  // iteration or more.
+  // Query the presence detection status
   bool presence = sensor.checkPresence();
 
   // If presence == true, turn on the built-in LED.

examples/Basic/Basic.ino

@@ -57,10 +57,7 @@ void loop()
    * be missed.
    */
 
-  // Query the presence detection status -- this is
-  // kind of slow since it communicates via serial.
-  // This can slow your loop down up to 100ms per
-  // iteration or more.
+  // Query the presence detection status
   bool presence = sensor.checkPresence();
 
   // If presence == true, turn on the built-in LED.