Secondary Installation for *nix

The install.sh script allows the user to chose the installation location. But the config will always be installed globally, meaning using it for secondary installations requires additional steps.

This MR changes this by installing the config into the etc directory of the prefix. But because the FPC looks up the install etc directory relative to it's real path, and it is only symlinked into the bin directory, the actual lookup would search in $PREFIX/lib/fpc/etc instead of $PREFIX/etc. To fix this, instead of symlinking, the fpc is now copied into the $PREFIX/bin directory instead.

Now when entering a custom path, like /opt/fpc it will create a completely self sufficient secondary installation instead of interfering with the system wide config