Add support for PHP classes in JsonPointer

Makefile

@@ -3,7 +3,7 @@ phar:
 
 docker56-composer-update:
 	test -f ./composer.phar || wget https://getcomposer.org/composer.phar
-	docker run -v $$(pwd):/code php:5.6-cli bash -c "apt-get update;apt-get install -y unzip;cd /code;php composer.phar update --prefer-source"
+	docker run --rm -v $$(pwd):/code php:5.6-cli bash -c "apt-get update;apt-get install -y unzip;cd /code;php composer.phar update --prefer-source"
 
 docker56-test:
-	docker run -v $$(pwd):/code php:5.6-cli bash -c "cd /code;php vendor/bin/phpunit"
+	docker run --rm -v $$(pwd):/code -w /code php:5.6-cli php vendor/bin/phpunit

README.md

@@ -231,6 +231,12 @@ $patch->apply($original);
 $this->assertEquals($diff->getRearranged(), $original);
 ```
 
+## PHP Classes as JSON objects
+
+Due to magical methods and other restrictions PHP classes can not be reliably mapped to/from JSON objects.
+There is support for objects of PHP classes in `JsonPointer` with limitations:
+* `null` is equal to non-existent
+
 ## CLI tool
 
 Moved to [`swaggest/json-cli`](https://github.com/swaggest/json-cli)