enhance bodyfile output

[joachimmetz]

• add signature - Added signature to bodyfile output #55 #57
• extend character escaping for characters special Unicode and non-Unicode characters - bodyfile: extend character escaping for characters special Unicode and non-Unicode characters #77
• add time zone information for FAT and equivalent # time zone: Europe/Amsterdam
• add information about application that created the bodyfile (name and version)
• handle date and time values with a special meaning, e.g. 0 as not set