%1, %2, ..., %N placeholders are used through all files and are replaced
with various article's properties in run-time when needed.

Here is overview of all placeholders used throughtout the skin:
  Common placeholders:
    %data% - is replaced by current absolute path to user data folder.

  html_wrapper.html:
    %style% - Skin-wide CSS, will be replaced by custom CSS if skin provides it in file "html_style.css".
    %1 - Title of the article.
    %2 - Body of the preview which is composed from:
            - single html_single_message.html (single article preview),
            - multiple html_single_message.html (newspaper mode).

  html_single_message.html:
    %1 - Title of the article.
    %2 - "Written by" text.
    %3 - URL of the article.
    %4 - Body of the article.
    %5 - Date/time of the article.
    %6 - Attachments (composed from html_enclosure_every.html).
    %7 - Attached pictures (composed from html_enclosure_image.html).

  html_adblocked.html:
    %1 - Title of the page. This page is used when the website is entirely blocked by AdBlock.
    %2 - Description of what and why was blocked.

  html_enclosure_every.html:
    %1 - URL of the attached media file.
    %2 - Attachment symbol.
    %3 - MIME type of the attachment.

  html_enclosure_image.html:
    %1 - URL of the attached picture file.
    %2 - MIME type of the picture.
    %3 - height of the picture thumbnail to be displayed which is loaded from application settings.
