Instrument the KSPe Install Checker to detect when the user deleted the Add'On Directory and kill yourself from GameData

[Lisias]

Users willing to remove KSPe are being bitten by 000_KSPe.dll that is usually left behind after deleting GameData/000_KSPe.

Instrument the KSPe.InstallChecker (aka 000_KSPe.dll) to detect when the main distribution is removed, and then remove 001_KSPe.dll to avoid KSPe from being installed on the rig.

The 000_KSPe.dll itself will linger on GameData, as It can't remove itself while running and once it's not running, it can't remove itself neither. This thing should be left on a completely dormant way, and a message on KSP.log should be issue telling the user that he can remove the file manually if desired.

[Lisias]

Implemented on commit 237b957