Edit HelpCommandMerge.png and HelpCommandMergeFastForward.png to overlay better

Help images in FormMergeBranch had visual elements in different locations.
Put visual elements in same location in both images to not distract on mouse over.
Merge pull request #1619 from mdonatas/FormMergeBranch-help-images

FormMergeBranch help images should overlay better
Dialog windows moved to appropriate subfolders
Translation updated