Replace hardcoded <object> and <img> widths with percentages.

Not totally untested, but …
Less pretending ;)
Let's do some cleanup along the way.

 * move some more clearly .post-specific styles over to partial
 * remove image scaling for blockquote images – max-width instead of "hardcoded full width"
 * add comments
 * order
Add height:auto.
Add "typography" partial.
Let there be partials.
masonite.sass finally only loads partials.
Whitespace.
Readability.
Tidy webkit-scrollbar styles.
Fix scrollbar-background for Safari.
Fix horizontal scrollbar height. Tsk!
Improve styles for audio player meta.
Tidy bits .footer CSS.
Minor reorganization.
Update changelog.
Add "dedicated" photoset markup.
Update changelog.
When not in "custom trigger" mode, position infinite-scrolls "loading screen" in #copyright.
Fix loading screen position for .centered-content.header-left.