Don't ignore the entire support/build directory.

support/build/.gitignore has more precise patterns.
Set ColladaLoader options from the caller instead of modifying the source.

This restores ColladaLoader.js to the upstream state, except for the
patch to honor Collada document names:

  844c844
  < obj.name = node.id || "";
  ---
  > obj.name = node.name || node.id || "";
Don't rotate Collada objects after import.

ColladaLoader's axis conversion will take care of this, and the
correction would also incorrectly appear in the node3 transform.

References #1680, #1556.