Don't allow a file to be added to deleting list twice

This could happen if you try and delete a file with a croppa-style suffix.  It would be in the array twice, once as the source, and once for matching the pattern.

Fixes #48

Also, I am explicitly checking that files begin with the passed filename.  And I added a new unit test

src/Bkwld/Croppa/Croppa.php

@@ -200,8 +200,12 @@ public function findFilesToDelete($url, $delete_original = true) {
 		$parts = pathinfo($src);
 		$files = scandir($parts['dirname']);
 		foreach($files as $file) {
-			if (strpos($file, $parts['filename']) === false || !preg_match('#'.$this->pattern().'#', $file)) continue;
-			$deleting[] = $parts['dirname'].'/'.$file;
+			$path = $parts['dirname'].'/'.$file;
+			if (strpos($file, $parts['filename']) === 0 
+				&& !in_array($path, $deleting)
+				&& preg_match('#'.$this->pattern().'#', $file)) {
+				$deleting[] = $path;
+			}
 		}
 
 		// Return the list

tests/TestDelete.php

@@ -46,4 +46,9 @@ public function testBadURL() {
 		$this->assertEquals(0, count($this->croppa->findFilesToDelete('whatever.dude')));
 	}
 
+	// https://github.com/BKWLD/croppa/issues/48
+	public function testFilenameWithDimensions() {
+		$this->assertEquals(array(vfsStream::url('dir/me-200x100.jpg')), $this->croppa->findFilesToDelete('me-200x100.jpg'));
+	}
+
 }