Merging DRUPAL-6--3 into HEAD for 7.x work. Some manually-resolved merge

conflicts.

Conflicts:
	contexts/terms.inc
	docs/sample_plugin_ct.inc
	help/plugin-style.html
	help/plugins-style.html
	plugins/layouts/threecol_33_34_33_stacked/threecol_33_34_33_stacked.inc
	plugins/layouts/twocol_bricks/panels-twocol-bricks.tpl.php
	plugins/styles/corners/rounded_corners.inc
	plugins/styles/default.inc
	plugins/styles/list.inc