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

diff.h

@@ -194,6 +194,11 @@ struct diff_options {
 	FILE *file;
 	int close_file;
 
+#define OUTPUT_INDICATOR_NEW 0
+#define OUTPUT_INDICATOR_OLD 1
+#define OUTPUT_INDICATOR_CONTEXT 2
+	char output_indicators[3];
+
 	struct pathspec pathspec;
 	pathchange_fn_t pathchange;
 	change_fn_t change;