The van der Waals radius must equal the Coulomb radius with Verlet

This patch fixes an issue that can occur when using g_tune_pme
with a Verlet pair-list .tpr input file. If the .tpr itself has
large cutoffs (e.g. 1.2 nm) and one asks g_tune_pme to scale
_down_ the Coulomb radius, the van der Waals radius is not
scaled down with the Coulomb radius (only upscaling worked).
One ends up with an unusable .tpr file because rVdW != rCoul.
This patch ensures that van der Waals and Coulomb radii
are always equal with Verlet pair-lists. Fixes #1460. Thanks
to Joao Rodrigues for reporting the issue!

Change-Id: I5ef30e71a35cd83838040057e16e52e09ea82e9a
Avoid cross product with zero vector in rotational pulling.

Fixes #1431 (rotation/flex-t regression test failing on BG/Q)

In do_flex_lowlevel() we checked (by mistake!) for xj-xcn being
zero, although we need to check for yj0-ycn being zero, since
we use yj0-ycn in a cross product in the following lines of code.
I now also replaced the direct check (0 == norm(...)) by checking
what gmx_numzero(norm(...)) returns. The latter replacement
was also applied in the do_flex2_lowlevel() routine. Note that there
the check for small xj-xcn was and is actually correct.

Change-Id: I972b6d67a81e30f297db286cd2224f66753a20aa
Merge branch release-4-6

Conflicts:
	src/gromacs/pulling/pull_rotation.c
Adopted the bugfixes from release-4-6

Uncrustified incoming code

Change-Id: I7d90bb49ef83750b9607f677e97a94f2b5793eeb
Merge "Merge branch release-4-6"