Merge remote-tracking branch 'github_origin/ThreeThreeOne' into github_sandbox_threethreeone
MOSYNC-3338: implemented the insert child functionality for horizontal and vertical layouts; MOSYNC-3354: remove child now works as it should (every child is shifted inside the grid structure after a remove)
Merge remote-tracking branch 'github_origin/ThreeThreeOne' into github_sandbox_threethreeone
MOSYNC-3355: inside a horizontal layout the default stack panel orientation should be Horizontal (without being set, the default was Vertical)
Merge pull request #501 from spiridon-alexandru/ThreeThreeOne

MOSYNC-3338; MOSYNC-3354; MOSYNC-3355