New strings in Orca

[Joanmarie Diggs <joanmarie diggs gmail com>]

Hi all.

Just... one... more... string. Well, actually, three more strings.
Sorry! This is to implement bgo 593666.

  #. Translators: this is for navigating among separators, such as the
  #. <hr> tag, in a document.
  #.
  #: ../src/orca/structural_navigation.py:3152
  msgid "Goes to previous separator."
  msgstr ""

  #. Translators: this is for navigating among separators, such as the
  #. <hr> tag, in a document.
  #.
  #: ../src/orca/structural_navigation.py:3157
  msgid "Goes to next separator."
  msgstr ""

  #. Translators: this is for navigating document content by
  #. moving amongst separators (e.g. <hr> tags). This string
  #. is what Orca will say if there are no more separators
  #. found.
  #.
  #: ../src/orca/structural_navigation.py:3205
  msgid "No more separators."
  msgstr ""

Thanks for all your work!
--joanie