Fix unininstall if installed to non-default folder

* hptool/os-extras/win/template/Nsisfile.nsi.mu

In either 32- or 64-bit installations, if the user
chooses a non-default install location, a recent
change caused the uninstall to always revert to the
default location.  This change fixes that problem.
Clarify 'isInstall' parameter of the do64Stuff macro
Update list of of packages shipped with GHC 7.8.3

Also, for easier comparison, list packages in same order as:

./ghc-7.8.3/inplace/bin/ghc-pkg --no-user-package-db list