New and updated Mursten-era parts

[Magnus Forsberg]

• 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.
  

I have used your design, and made a common subfile to be used in both parts. And fixed 716b.
https://www.ldraw.org/cgi-bin/ptdetail.c...s/716b.dat