When adding Port or URL alias default the alias type

When viewing the Port or URL aliases tab, and pressing "+" (add), make the default alias type match the Port or URL tab from which the user pressed "+".
It was annoying that when I was in the Aliases, Ports tab and pressed "+", the aliases edit screen would default the new alias type to "Host".
This backports easily to 2.1 branch (which is what I used to test).