ENH: Fix help button alignment in Builder dialogs

In Builder's properties dialogs the alignment of the help buttons did
not match the okay and cancel buttons. The cause for this was that the
flags for Sizer's Add() method were passed to the wrong parameter. This
was fixed by adding the missing passing of 0 for the skipped parameter.
Merge pull request #406 from philippwiesemann/master

ENH: Fix help button alignment in Builder dialogs
Merge pull request #409 from jeremygray/master

BF: better handling of mono sound files in SoundPyo; closes #408
BF: fixed further problem with ImageStims appearing grey in certain cases

Only if they had a size being set, and an image being set initially to "sin"
NF: Rating Scale flipVert option

- mirror image in vertical direction, eg, for fMRI