Update freeplane to 1.6.7

[commitay]

After making all changes to the cask:

• brew cask audit --download {{cask_file}} is error-free.
• brew cask style --fix {{cask_file}} left no offenses.
• The commit message includes the cask’s name and version.

Additionally, if updating a cask:

• sha256 changed but version stayed the same (what is this?).
  I’m providing public confirmation below.

[reagle]

Since upgrading to this version, I can no longer open mindmaps via QuickSilver launcher or open from the command line. It still launches FreePlane, but it starts with a new mindmap, not the one I specified.
NOTE: this only happens if there is no FreePlane running. If the app is already running, these invocations will result in the specified file opening.