BUGFIX: regex-escape strings to prevent regex syntax errors

Apply preg_quote to each generator name and to $this->Name so that their use in a
regular expression will not cause run-time errors.

Provided fixture and test.

model/Image.php

@@ -361,12 +361,12 @@ class Image extends File {
 		foreach($methodNames as $methodName) {
 			if(substr($methodName, 0, 8) == 'generate') {
 				$format = substr($methodName, 8);
-				$generateFuncs[] = $format;
+				$generateFuncs[] = preg_quote($format);
 			}
 		}
 		// All generate functions may appear any number of times in the image cache name.
 		$generateFuncs = implode('|', $generateFuncs);
-		$pattern = "/^(({$generateFuncs})\d+\-)+{$this->Name}$/i";
+		$pattern = "/^(({$generateFuncs})\d+\-)+" . preg_quote($this->Name) . "$/i";
 
 		foreach($cachedFiles as $cfile) {
 			if(preg_match($pattern, $cfile)) {

tests/model/ImageTest.php

@@ -93,4 +93,13 @@ class ImageTest extends SapphireTest {
 		$actual = $imageSecond->getHeight();
 		$this->assertEquals($expected, $actual);
 	}
+	
+	function testGeneratedImageDeletion() {
+		$image = $this->objFromFixture('Image', 'imageWithMetacharacters');
+		$image_generated = $image->SetWidth(200);
+		$p = $image_generated->getFullPath();
+		$this->assertTrue(file_exists($p));
+		$image->deleteFormattedImages();
+		$this->assertFalse(file_exists($p));
+	}
 }

tests/model/ImageTest.yml

@@ -12,3 +12,7 @@ Image:
     imageWithoutTitleContainingDots: 
         Filename: assets/ImageTest/test.image.with.dots.png
         Parent: =>Folder.folder1
+    imageWithMetacharacters:
+        Title: This is a/an image Title
+        Filename: assets/ImageTest/test_image*).png
+        Parent: =>Folder.folder1