added override before the init in the machine.swift.motemplate

Beta5 now request the override...
Also changed the pragma marks to // MARK: 
Right... I understand // MARK: is the replacement for //pragma mark in Swift.  The original //pragma marks in this source code were //pragma mark - (note the hyphen), including the divider.  The hyphen works in the new // MARK: syntax as well, so it seem appropriate to maintain it rather than remove it.