10_BETA: Nice QOL improvements to the installer

[Lloyd Parkes <lloyd%must-have-coffee.gen.nz@localhost>]

Hi all,
It's been a while since I've run the NetBSD installer, so I don't now 
how recent the changes I've seen are, but I do like them.

I was installing on amd64 and the installer let me choose either MBR or 
GPT, which is nice. The NUC I was installing on is old enough that it 
can only UEFI boot from wd0 and some OSes don't allow a UEFI install 
from a BIOS booted USB installed.

I also noticed that the installer knew where the install files were 
locally on the USB stick and just installed them. Is that new?

I specifically chose a NUC without a hardware RNG so that I could test a 
tweak to the /etc/rc.d/entropy script and was pleasantly surprised to 
see that the installer detected this and applied a giant clue hammer. 
That was very nice.

Cheers,
Lloyd