patch[GSoC] Add configuration options for some commonly used command-line options

> git-log will be run as 'git-log --no-merges'.
> 
> Signed-off-by: Koosha Khajehmoogahi <koosha@posteo.de>
> ---
>  Documentation/config.txt | 3 +++
>  builtin/log.c            | 8 ++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 1530255..7775b8c 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -1735,6 +1735,9 @@ log.showroot::
>  	Tools like linkgit:git-log[1] or linkgit:git-whatchanged[1], which
>  	normally hide the root commit will now show it. True by default.
>  
> +log.showmerges::
> +	If true, merges will be shown in the log list. True by default.
> +
>  log.mailmap::
>  	If true, makes linkgit:git-log[1], linkgit:git-show[1], and
>  	linkgit:git-whatchanged[1] assume `--use-mailmap`.
> diff --git a/builtin/log.c b/builtin/log.c
> index dd8f3fc..bb36f61 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -31,6 +31,7 @@ static const char *default_date_mode = NULL;
>  
>  static int default_abbrev_commit;
>  static int default_show_root = 1;
> +static int default_max_parents = -1;
>  static int decoration_style;
>  static int decoration_given;
>  static int use_mailmap_config;
> @@ -108,6 +109,7 @@ static void cmd_log_init_defaults(struct rev_info *rev)
>  	rev->diffopt.stat_graph_width = -1; /* respect statGraphWidth config */
>  	rev->abbrev_commit = default_abbrev_commit;
>  	rev->show_root_diff = default_show_root;
> +	rev->max_parents = default_max_parents;
>  	rev->subject_prefix = fmt_patch_subject_prefix;
>  	DIFF_OPT_SET(&rev->diffopt, ALLOW_TEXTCONV);
>  
> @@ -390,6 +392,12 @@ static int git_log_config(const char *var, const char *value, void *cb)
>  		default_show_root = git_config_bool(var, value);
>  		return 0;
>  	}
> +
> +	if (!strcmp(var, "log.showmerges")) {
> +		default_max_parents = git_config_bool(var, value) ? -1 : 1;
> +		return 0;
> +	}
> +
>  	if (skip_prefix(var, "color.decorate.", &slot_name))
>  		return parse_decorate_color_config(var, slot_name, value);
>  	if (!strcmp(var, "log.mailmap")) {
> 

> This patch adds a 'showmerges' config. option for git-log.
> This option determines whether the log should contain merge
> commits or not. In essence, if this option is set to true,
> git-log will be run as 'git-log --no-merges'.
>
> Signed-off-by: Koosha Khajehmoogahi <koosha@posteo.de>
> ---
>  Documentation/config.txt | 3 +++
>  builtin/log.c            | 8 ++++++++
>  2 files changed, 11 insertions(+)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 1530255..7775b8c 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -1735,6 +1735,9 @@ log.showroot::
>  	Tools like linkgit:git-log[1] or linkgit:git-whatchanged[1], which
>  	normally hide the root commit will now show it. True by default.
>  
> +log.showmerges::
> +	If true, merges will be shown in the log list. True by default.