Lots of improvements and restore settings instructions

Unfortunately Webextensions do no carry over the settings storage method the previous add-on type was making use (simple-storage) which results in updated versions having only default settings. As a workaround a guide has been provided instructing users how to restore the settings manually; it can be found here: https://github.com/ParticleCore/Particle/wiki/Restore-settings

It is an unfortunate situation but unavoidable since Mozilla did not provide any methods to do this automatically.

Other improvements have been made, memory use has been reduced slightly, YouTube recently changed the suggested videos sidebar and this version includes an update for that as well, cinema and fullbrowser modes now engage when the settings were enabled while the video was not playing, and fullbrowser mode will no longer change sizes when exiting via button click.

Additionally YouTube is now correcting the aspect ratio of certain videos, this change was being undone by previous YT+ styling rules which have now been removed in this version so the correction process can be done as normal.