Finalized page range input

Added clear page range function, added unit test and updated docs

Author: DaanDeSmedt

README.md

@@ -170,6 +170,13 @@ $ghostscript->setPageEnd(int $page);
 ```
 
 
+## Clear specified page range
+
+```php
+$ghostscript->clearPageRange();
+```
+
+
 ## Subsample antialiasing
 
 These options control the use of subsample antialiasing. Their use is highly recommended for producing high quality rasterizations of the input files. 

composer.json

@@ -27,5 +27,8 @@
     "require": {
         "php": ">= 7.0.0",
         "mikehaertl/php-shellcommand": "^1.2"
+    },
+    "scripts": {
+        "test": "vendor/bin/phpunit --verbose --configuration phpunit.xml"
     }
 }

src/PHPGhostscript/Ghostscript.php

@@ -448,6 +448,19 @@ public function setPages(int $startPage, int $endPage) : Ghostscript
         return $this;
     }
 
+    /**
+     *  Clears the page range
+     *
+     * @return self
+     */
+    public function clearPageRange() : Ghostscript
+    {
+        $this->setPageStart(null);
+        $this->setPageEnd(null);
+        return $this;
+    }
+
+
 
     /**
      * Set the render box mode

tests/PHPGhostscript/PHPGhostscriptTest.php

@@ -171,6 +171,21 @@ public function testMerging()
         $this->assertTrue($result);
     }
 
+    public function testClearPageRange() {
+        $ghostscript = new Ghostscript();
+        $this->assertNull($ghostscript->getPageStart());
+        $this->assertNull($ghostscript->getPageEnd());
+        
+        $ghostscript->setPageStart(2);
+        $ghostscript->setPageEnd(10);
+        $this->assertEquals(2, $ghostscript->getPageStart());
+        $this->assertEquals(10, $ghostscript->getPageEnd());
+
+        $ghostscript->clearPageRange();
+        $this->assertNull($ghostscript->getPageStart());
+        $this->assertNull($ghostscript->getPageEnd());
+    }
+
     public function testMerging2()
     {
         $outputFile = __DIR__ . DIRECTORY_SEPARATOR . 'output' . DIRECTORY_SEPARATOR . 'merge2.pdf';