added option to set line color

.gitignore

@@ -1,3 +1,4 @@
+.idea/
 demo/*.jpg
 demo/*.pgm
 demo/temp/

src/Gregwar/Captcha/CaptchaBuilder.php

@@ -28,6 +28,11 @@ class CaptchaBuilder implements CaptchaBuilderInterface
      */
     protected $textColor = array();
 
+    /**
+     * @var array
+     */
+    protected $lineColor = array();
+
     /**
      * @var array
      */
@@ -229,6 +234,13 @@ public function setBackgroundColor($r, $g, $b)
         return $this;
     }
 
+    public function setLineColor($r, $g, $b)
+    {
+        $this->lineColor = array($r, $g, $b);
+
+        return $this;
+    }
+
     /**
      * Sets the ignoreAllEffects value
      *
@@ -257,8 +269,18 @@ public function setBackgroundImages(array $backgroundImages)
      */
     protected function drawLine($image, $width, $height, $tcol = null)
     {
+        $red = $this->rand(100, 255);
+        $green = $this->rand(100, 255);
+        $blue = $this->rand(100, 255);
+
+        if (!empty($this->lineColor)) {
+            $red = $this->lineColor[0];
+            $green = $this->lineColor[1];
+            $blue = $this->lineColor[2];
+        }
+
         if ($tcol === null) {
-            $tcol = imagecolorallocate($image, $this->rand(100, 255), $this->rand(100, 255), $this->rand(100, 255));
+            $tcol = imagecolorallocate($image, $red, $green, $blue);
         }
 
         if ($this->rand(0, 1)) { // Horizontal