Sync up BCF XML with BCF API

[GeorgDangl]

BCF API

✔ = Present in BCF XML
❌ = Missing in BCF XML

• buildingSMART/BCF-API@84af26d#diff-ac8d0a54775f67811b0c24e33fd2fa997d59a30af88b696789daf117e3095391
  buildingSMART/BCF-API@3885f36
  -> Custom fields
  ❌

• buildingSMART/BCF-API@d92ce0d
  -> Change url parameter names

• buildingSMART/BCF-API@5cbce2f
  -> Topic relations
  ✔ (Has already been there in BCF XML)

• buildingSMART/BCF-API@3b6653c
  -> parent / child relations
  ❌ -> Add topic relation types #390

• buildingSMART/BCF-API@c2584b0
  -> Viewpoint audit info
  ❌ -> Add audit info on viewpoints #389

• buildingSMART/BCF-API@fa9aa93
  -> translucency
  ✔

• buildingSMART/BCF-API@5659983
  -> Remove BIM snippet
  ✔

• buildingSMART/BCF-API@f4f5035
  -> Topic files in viewpoints
  ✔

• buildingSMART/BCF-API@0f3e266
  -> id and name properties
  ❌ -> We've discussed this and came to the conclusion that we don't port id properties separately to the XML exchange. Bringing several XML files to the same project, each having their own ids, would make combining those very complicated and you would have to maintain several external ids for the same properties. If they would not be maintained, then having the ids would not provide any benefit.
  Add typed topic types #388

• buildingSMART/BCF-API@6ce1ee5
  -> markers
  ❌ -> Add markers to viewpoints #387

• buildingSMART/BCF-API@edfde64
  -> Main viewpoint guid
  ✔

Just for internal tracking right now😀