hfsexplorer.nsi: Make installer/uninstaller use same ShellVarContext.

We want to install our shortcuts in the "All Users" start menu
hierarchy, and not the user-specific one. Uninstaller was caught
attempting to uninstall start menu shortcuts from the user-specific
hierarchy while they had been installed into the "All Users" hierarchy,
thus failing to uninstall the start menu shortcuts.
hfsexplorer.nsi: Added 'bin' directory to directories to uninstall.

Also sorted list of directories to uninstall.