Only add/remove from htaccess file when necessary.

 Ensures that we only add/remove from the htaccess file when there's an
 option enabled that has associated htaccess rules, or when the htaccess
 file contains rules that should be removed because we've disabled all
 options that require htaccess rules.

See wpsharks/comet-cache#641

src/includes/closures/Plugin/HtaccessUtils.php

@@ -10,6 +10,15 @@
 */
 $self->htaccess_marker = 'WmVuQ2FjaGU';
 
+/*
+* Plugin options that have associated htaccess rules.
+*
+* @since 15xxxx Improving `.htaccess` tweaks.
+*
+* @return array Plugin options that have associated htaccess rules
+*/
+$self->options_with_htaccess_rules = array('cdn_enable');
+
 /*
  * Add template blocks to `/.htaccess` file.
  *
@@ -26,6 +35,12 @@
     if (!$self->options['enable']) {
         return true; // Nothing to do.
     }
+    if (!$self->needHtaccessRules()) {
+        if($self->findHtaccessMarker()) { // Do we need to clean up previously added rules?
+            $self->removeWpHtaccess(); // Fail silently since we don't need rules in place.
+        }
+        return true; // Nothing to do; no options enabled that require htaccess rules.
+    }
     if (!$self->removeWpHtaccess()) {
         return false; // Unable to remove.
     }
@@ -116,6 +131,25 @@
     return $file;
 };
 
+/*
+ * Determines if there are any plugin options enabled that require htaccess rules to be added.
+ *
+ * @since 15xxxx Improving `.htaccess` tweaks.
+ *
+ * @return bool True when an option is enabled that requires htaccess rules, false otherwise.
+ */
+$self->needHtaccessRules = function () use ($self) {
+    if(!is_array($self->options_with_htaccess_rules)) {
+        return false; // Nothing to do.
+    }
+    foreach ($self->options_with_htaccess_rules as $option) {
+        if ($self->options[$option]) {
+            return true; // Yes, there are options enabled that require htaccess rules.
+        }
+    }
+    return false; // No, there are no options enabled that require htaccess rules.
+};
+
 /*
  * Utility method used to unlock and close htaccess file resource.
  *