assorted improvements

[spacek531]

addresses #2 #3 #4 #8 #9 #10

• Make child hiding recursive to properly handle deep hierarchies
• Adds flag for null sub-component
• Addresses 3 by adding the ability to specify a bounding box
• Adds flag to render sub-component
• Uses world matrix for all distance calculations
• Implements file versioning
• Shifts all component and sub-component indices to 0-index
• Renames roll to tilt
• Adds offsets for each vehicle type, only rail is supported currently
• Reword some properties
• Tweak UI