New and updated Mursten-era parts

[N. W. Perry]

I am working on a number of parts from the very early years that are either missing from the library or in need of revision. A number of issues arise about renumbering, part naming, etc., so I've compiled everything here and placed bullets beside those points requiring attention or input.

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1x8 brick
The earliest 1x8 bricks had two internal ribs; the existing 925.dat has three, a slightly newer design. I have submitted the 2-rib version as 925a.dat, along with a subfile for patterning.

• I propose the existing 925.dat should be obsoleted and renumbered 925b.dat, and "with 3 internal ribs" should be added to its name.
  
• Many of the existing patterns for 925 would have appeared with 925a, either instead of or along with 925b. Given the difficulty of documenting this with any precision, it is probably not worth the effort.
  

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4x4 corner bricks
The two versions with one slot, u8009b.dat and u8009c.dat, are missing. I will build and submit these.

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Macaroni bricks
The 4x4 half-round brick without cutouts was missing from the library. I have submitted it as 716a.dat, and the existing 716 has been obsoleted and renumbered 716b.dat.

• This matches the numbering of the 2x2 quarter-round bricks 3063a (without) and 3063b (with).
  
• But the names do not match: 716 has "cutouts" whereas 3063 has "stud notches". Should this be fixed?
  

With this part I took the opportunity to introduce the empty 1-48chrd.dat and 6 other new primitives, mostly rings. It required a surprisingly complete overhaul, including fixing an overlap of ring prims on the bottom surface.

• I did not fix this overlap in 716b.dat, and there are a few other geometry issues besides. A potential project, for anyone seeking one.
  

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Doors & windows
The ABB door is confirmed to be a single part with a two-sided design, rather than two different parts. That part has been submitted as u8040.dat, and the existing u8013.dat and u8014.dat have been obsoleted.

• Possible "needs work": the raised features on this part should really be outlines rather than solid shapes. Perhaps in a future revision…
  

The "3rd gen" windows and doors (studless, no glass, HO scale) have all been revised and submitted with improved geometry of the tabs, as discussed here.

The 1x2x3 door came in both right- and left-handled varieties. I've submitted the missing right-handled version as u8012b.dat.

• The existing u8012 should be renumbered u8012a.dat and "Left" should be added to its name.
  

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Garage door and frame
The studless garage door frame with tabs for slotted bricks is not in the library. There are two variants, both to be submitted, with proposed numbering:

• 821a.dat: with full tabs
  
• 821b.dat: with partial tabs
  
• The existing 821.dat should be renumbered 821c.dat and "with Studs" should be added to its name.
  

The correct door for this period is 822a.dat. However, with all the various counterweights in the library, none is the correct match. They should have pin holes and they are a different shape.

• Should these be new suffixed variants (R and L) of u9187, or given a new base number?
  
• These would be combined with the door into a new shortcut, 822ac02.dat.