Merge branch 'jk/color-variable-fixes'

Some places in the code confused a variable that is *not* a boolean
to enable color but is an enum that records what the user requested
to do about color.  A couple of bugs of this sort have been fixed,
while the code has been cleaned up to prevent similar bugs in the
future.

* jk/color-variable-fixes:
  config: store want_color() result in a separate bool
  add-interactive: retain colorbool values longer
  color: return bool from want_color()
  color: use git_colorbool enum type to store colorbools
  pretty: use format_commit_context.auto_color as colorbool
  diff: stop passing ecbdata->use_color as boolean
  diff: pass o->use_color directly to fill_metainfo()
  diff: don't use diff_options.use_color as a strict bool
  diff: simplify color_moved check when flushing
  grep: don't treat grep_opt.color as a strict bool
  color: return enum from git_config_colorbool()
  color: use GIT_COLOR_* instead of numeric constants

combine-diff.c

@@ -749,7 +749,7 @@ static void show_line_to_eol(const char *line, int len, const char *reset)
 
 static void dump_sline(struct sline *sline, const char *line_prefix,
 		       unsigned long cnt, int num_parent,
-		       int use_color, int result_deleted)
+		       enum git_colorbool use_color, int result_deleted)
 {
 	unsigned long mark = (1UL<<num_parent);
 	unsigned long no_pre_delete = (2UL<<num_parent);