theme_tern_gray ternary theme, gray theme  theme_tern_rgbg ternary theme, red green blue with
  gray background
  theme_tern_rgbw ternary theme, red green blue with
  white background
  theme_tern_bw ternary theme black and white
  Convenience functions to assist in the rapid modification
  of key theme elements.
  theme_noarrows is a function that apepnds to the
  current theme a flag to switch OFF the ternary arrows
  theme_showarrows is a function that apepnds to the
  current theme a flag to switch ON the ternary arrows
  theme_tern_nogrid ternary theme, no minor grids.
  theme_tern_nogrid ternary theme, no major grids.
  theme_tern_nogrid ternary theme, no major or minor
  grids.
  theme_clockwise is an alias for
  tern_clockwise
  theme_anticlockwise is an alias for
  tern_anticlockwise
  theme_counterclockwise is an alias for
  tern_counterclockwise