forbid theme's config to override main config

[3100]

This issue is similar to #756 but is a simpler idea.

I want to use a same theme in some blogs without doing customize the theme's config file. One blog's url contains subdirectory and another's does not, so the following menu config does not work in the first case:

menu:
  Home: /
  Archives: /archives

I found #583 as a similar issue but it does not solve the problem. ( if you click the title of an article and then click archive link, your browser will show 404 because it is 'relative' link to the article. )
And another thing, if you set your menu to your main config, it will be overiden by your theme' config. This seems weird to me. If there is no reasonable cause, it would be better if the main config were always prior. If so, I have only to change some blog's main config like below:

menu:
  Home: /subdirectory/
  Archives: /subdirectory/archives

[3100]

Sorry, I've detected where this priority rule is coded and understood that theme_config is suited for this case.

Locals.prototype.theme = _.extend({}, config, theme.config, config.theme_config);

in _/lib/hexo/index.js_

Now I edited my main config like below and it works perfectly:

theme_config:
  menu:
    Home: /subdirectory/
    Archives: /subdirectory/archives

[dontpanic92]

I don't think writing 'subdirectory' many times is a good idea because we have already pointed out the root directory in 'root' option.