fix flush command handling

lib/g2core-api.js

@@ -424,7 +424,7 @@ class G2coreAPI extends EventEmitter {
       this.emit('setupDone');
 
       // Allow data to be sent. We'll start with 5 lines to fill the buffer.
-      this.linesRequested = 5;
+      this._resetLinesRequested();
       this._sendLines();
     });
   }; // _completeConnection
@@ -467,7 +467,15 @@ class G2coreAPI extends EventEmitter {
     this.emit('sentLine', lastLineSent);
   }; // _sendLines
 
+
+  /**
+   * _resetLinesRequested - internal only
+   */
+  _resetLinesRequested() {
+    this.linesRequested = 5;
+  }; // _resetLinesRequested
 
+
   /**
    * flush - empty the send buffer, without sending what's left
    */
@@ -479,7 +487,7 @@ class G2coreAPI extends EventEmitter {
     this.lineBuffer.length = 0;
 
     // Reset line requested
-    this.linesRequested = 5;
+    this._resetLinesRequested();
 
     // Send a queue flush followed by an alarm clear
     this._write('\x04'); // send the ^D
@@ -603,6 +611,15 @@ class G2coreAPI extends EventEmitter {
         this.ignoredResponses++;
       }
       this._write(value);
+
+	  // handle flush command
+	  if(typeof value === 'string' && value.match(/^[!]+$/)) {
+		  this._resetLinesRequested();
+		  this.linesSent = 0;
+		  this.ignoredResponses = 0;
+		  this.lineBuffer.length = 0;
+	  }
+
       return;
     }