#371231 by JohnAlbin and EclipseGC: Rename clear-block CSS class to clearfix, which is the lingo that designers use for it.

#364777 by Eaton, EclipseGC, JohnAlbin, and Rob_Feature: Add a 'stripped down' CSS theme to core to demo Drupal's default markup. Say hello to stark.

#203323 by JirkaRybka, robertgarrigos, thePanz, c960657, and sun: Fix undefined index locale in install.php and clean up crufty code.

- Patch #270917 by catch, Bojhan, et al: renamed 'primary links' and 'secondary links' to 'main menu' and 'secondary menu' respectively.  Based on usability study conducted with the help of Bojhan.

- Patch #245115 by kkaefer, John Morahan, JohnAlbin et al: after a long discussion we've decided to make the concatenation operator consistent with the other operators.

- Patch #216072 by recidive, David Rothstein, ptalindstrom et al: switched from numeric block IDs to string IDs.

  The short explanation is that Drupal uses a lot of numeric deltas in the block system; blocks are identified by the 'module' and the 'delta'. In early Drupal, delta was numeric, but somewhere along the line it was changed to be possibly a string. In modern Drupal, block overrides are easily done via block-MODULE-DELTA.tpl.php.  The primary motivation to switch to string IDs everywhere is to make these deltas friendlier to themers:

    block-user-0.tpl.php --> block-user-navigation.tpl.php
    block-user-1.tpl.php --> block-user-login.tpl.php

  You get the picture.

- Patch #238528 by misamuelson, approved by Stefan: disabled menu items should not be opaque for usability.

#209663 by Matt V., ScoutBaker, Arancaytar: document that the modules and themes folders are only for core modules and themes

#208768 by dvessel, Arancaytar: language direction should be in the HTML source, so it is more accessible even without CSS

#194590 by scor, JirkaRybka, attiks, dvessel; with heavy testing by catch: fix a dozen issues with sticky table headers

#202821 by marco.robotangel: display messages above help in all core themes for consistent user feedback (usability)

#199809 by theborg: comment templates were not checking status properly (fix notice, allows themes to theme in-preview comments differently)