Better stylesheet management and user selection storage

Perhaps there could be a file(s) (JSON?) that maps template files and CSS files, which will help determine which styles relate to which templates, as well as which reply templates are associated with which "parent" templates

Here's a quick mock-up:

{
  "templates": {
    "kokoimg": {
      "filename": "kokoimg.tpl",
      "css_styles": ["Futaba", "Burichan"]
    },
    "kokotxt": {
      "filename": "kokotxt.tpl",
      "css_styles": ["Pseud0ch", "Pseud0ch sans-serif"]
    },
    "kokotxtreply": {
      "filename": "kokotxtreply.tpl",
      "parent_template": "kokotxt"
    }
  },
  "styles": {
    "Futaba": {
      "filename": "futaba.css"
    },
    "Burichan": {
      "filename": "burichan.css"
    },
    "Pseud0ch": {
      "filename": "pseud0ch.css"
    },
    "Pseud0ch sans-serif": {
      "filename": "pseud0ch2.css"
    }
  }
}

Then the PHP side could potentially use this info to:

generate the appropriate list of <link>s for each template
determine a prefix for the localstorage location that stores the user-selected style (e.g. style_kokotxt: Pseud0ch), as well as (for example) know to use style_kokotxt when kokotxtreply.tpl is used
generate JS that saves/loads the user-selected style to/from the appropriate localstorage location

Potential issues:

if the correct localstorage location isn't immediately known on page load, the screen may flash white (terrible for dark styles) or the page may temporarily appear with the wrong style
there might be an entirely different and better solution that I failed to think of

Heyuri / kokonotsuba

Better stylesheet management and user selection storage #155