Use 64-bit R to work around recent problems with 32-bit R

Squashed commit of the following:

commit 0a2ac7b27eb64a6db356a219fbf262cb6548ab2f
Author: Kirill Müller <kirill.mueller@ivt.baug.ethz.ch>
Date:   Wed Oct 29 15:14:26 2014 +0100

    un-ls

commit 8c024d862eff3a2da68df57f2708a85406f0072e
Author: Kirill Müller <kirill.mueller@ivt.baug.ethz.ch>
Date:   Wed Oct 29 14:20:03 2014 +0100

    need 64-bit!

commit 6312707b69ec9c19a52283f10b48ce5acb6c6802
Author: Kirill Müller <kirill.mueller@ivt.baug.ethz.ch>
Date:   Tue Oct 28 00:38:43 2014 +0100

    need 64-bit?

commit 66fdce658bf4b631bea3eadc9e0b35765be54639
Author: Kirill Müller <kirill.mueller@ivt.baug.ethz.ch>
Date:   Tue Oct 28 00:28:46 2014 +0100

    the answer

commit a25ea17ee8e12e0a2187f4e04a6960b39dd88240
Author: Kirill Müller <kirill.mueller@ivt.baug.ethz.ch>
Date:   Mon Oct 27 16:25:43 2014 +0100

    show directory contents