[Rd] Change windows installer default to only install 64 bit R

[Jeroen Ooms]

On Fri, Nov 9, 2018 at 5:47 PM Jim Hester <james.f.hester using gmail.com> wrote:
> We can remove much of this ambiguity by changing the default choice in
> the installer to only install the 64 bit version in the installer. If
> users do need the 32 bit version it is still simple for them to
> install it by checking the appropriate box during installation.

I tested the patch and confirm that this works as intended. By
default, the R installer will leave the "32-bit Files" unchecked on
Windows 64 machines.

I also think this proposal makes sense. Most users do not need 2
versions of R on their machine, and it is a common source of problems.
I agree with Jim that installing the 32bit version of R on 64bit
Windows would better be opt-in rather than default.