* Security improvements to TrustedUpdate: signing and verification of the
      version string along with the data payload for signed update files
      (consequently the positions of the DSA signature and version string fields
      have been swapped in the spec for the update file's header); router will
      no longer perform a trusted update if the signed update's version is lower
      than or equal to the currently running router's version.
    * Added two new CLI commands to TrustedUpdate: showversion, verifyupdate.
    * Extended TrustedUpdate public API for use by third party applications.