Allow multiple installations

[René Smit]

Currently, user has to install GPxPatch separately for each simulator he / she is using: GP3, GP3 2000 and / or GP4. Only the last of the installed GPxPatches can be uninstalled properly. Could it be possible to make the installer work, so that it could be possible for allowing user to enter all paths for each simulator he / she has installed, so a single installation could be used for possibly all of three sims? Uninstaller could work the same way, allowing to choose, which GPxPatches should be uninstalled.