write-editor-version in Editors

• (write-editor-version out out-base) -> boolean
     out : editor-stream-out% object
     out-base : editor-stream-out-base% object

  Writes version information to out-base in preparation for writing editor information to the stream out.

  The out argument is currently not used, but out-base should be the base for out. In the future, out may record information about the version for later version-sensitive output.

  The result is #t if the write succeeded, #f otherwise.