Merge branch '2897_mc_ext_updates'

Merge branch '2897_mc_ext_updates'

* 2897_mc_ext_updates:
  Ticket #1686: use 'see' utility for vieweing images
  Ticket #1686: use 'see' utility as default pdf viewer when found
  Ticket #1686: use dvicat if dvi2tty not found
  Ticket #2723: use libreoffice instead of ooffice, if found.
  Ticket #2739: add support of PAR archives.
  Ticket #2739: add support of epub format.
  Ticket #2739: add support of comic books.
  Ticket #2767: mc.ext: add support of ape, aac and wvm4a formats.
  Ticket #2895: add support of SVG images.
  Ticket #2890: make a choice between archivers for 7z.
  Ticket #2890: make a choice between archivers for arj.
  Ticket #2891: add support of .war archives.
  Ticket #2892: mc.ext: expand support of file extentions for source files
  Ticket #2894: add support of Gnumeric's spreadsheets.
  Ticket #2897: a lot of updates of mc.ext and ext.d.