I have installed LightSpark Flash Player alternative from what is called the official PPA: https://launchpad.net/~sparkers/+archive/ppa (I mean, I added this repository and then sudo apt-get install lightspark). But Firefox doesn't feel it. It looks exacly like when I hadn't installed LightSpark. In "Firefox - Addons - Plugins" there is no new entry. What should I do to really use Lightspark after installing it?