Merge branch 'sb/range-diff-colors'

The color output support for recently introduced "range-diff" command got tweaked a bit. * sb/range-diff-colors: range-diff: indent special lines as context range-diff: make use of different output indicators diff.c: add --output-indicator-{new, old, context} diff.c: rewrite emit_line_0 more understandably diff.c: omit check for line prefix in emit_line_0 diff: use emit_line_0 once per line diff.c: add set_sign to emit_line_0 diff.c: reorder arguments for emit_line_ws_markup diff.c: simplify caller of emit_line_0 t3206: add color test for range-diff --dual-color test_decode_color: understand FAINT and ITALIC