FIX Filenames must not contains non ascii char or we will get non ascii

char into the SMTP header.
FIX Do not encode subject if it is full ascii (not required)

test/phpunit/FunctionsLibTest.php

@@ -679,6 +679,26 @@ class FunctionsLibTest extends PHPUnit\Framework\TestCase
         $this->assertFalse($result);
     }
 
+    /**
+     * testDolAsciiCheck
+     *
+     * @return void
+     */
+    public function testDolAsciiCheck()
+    {
+    	// True
+    	$result=ascii_check('azerty');
+    	$this->assertTrue($result);
+
+    	$result=ascii_check('é');
+    	$this->assertFalse($result);
+
+    	$file=dirname(__FILE__).'/textutf8.txt';
+    	$filecontent=file_get_contents($file);
+    	$result=ascii_check($filecontent);
+    	$this->assertFalse($result);
+    }
+
     /**
      * testDolTrunc
      *