grep: Colorize selected, context, and function lines

Colorize non-matching text of selected lines, context lines, and
function name lines.  The default for all three is no color, but they
can be configured using color.grep.<slot>.  The first two are similar
to the corresponding options in GNU grep, except that GNU grep applies
the color to the entire line, not just non-matching text.

Signed-off-by: Mark Lodato <lodatom@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/grep.h b/grep.h
index 36919ee..2c4bdac 100644
--- a/grep.h
+++ b/grep.h
@@ -84,9 +84,12 @@
 	int color;
 	int max_depth;
 	int funcname;
+	char color_context[COLOR_MAXLEN];
 	char color_filename[COLOR_MAXLEN];
+	char color_function[COLOR_MAXLEN];
 	char color_lineno[COLOR_MAXLEN];
 	char color_match[COLOR_MAXLEN];
+	char color_selected[COLOR_MAXLEN];
 	char color_sep[COLOR_MAXLEN];
 	int regflags;
 	unsigned pre_context;