Fixed transparent background for ImageMagick in CCaptchaAction

thanks to @manuel-84
https://github.com/yiisoft/yii/pull/1464#issuecomment-12046268
Merge branch 'master' of https://github.com/yiisoft/yii

* 'master' of https://github.com/yiisoft/yii:
  Fixes #1867 Gii model generator tableName autocomplete
minor doc fixes
Fixes #1941 reset CHtml:: instad of hardcoded value
send CHtml::errorCss to JS file
added changelog
Merge pull request #1944 from mdomba/1941-CACtiveForm-reset-errorCss

Fixes #1941 cActiveForm form reset
[ci skip]
Fixes #1942 CActiveForm client validation
Merge pull request #1946 from mdomba/1942-CActiveForm-clientvalidation

Fixes #1942 CActiveForm client validation
[ci skip]
Improved docs for CArrayDataProvider::$keyField

Issue #1943
added `@todo` comments to gii model template

Fixes #1951
Throw exception on missing PDO class in CDbConnection

issue #645
updated german translation files
updated copyright year in docs
ru: fixed broken link in the guide
zii: jQuery UI documentation links updated (jqueryui.com links were changed after their site update).
zii widgets: API and demo page links in the PHPDocs are now clearly separated and explicitly described.
Merge pull request #1963 from resurtm/JUI-links

zii: jQuery UI documentation links updated
[ci skip]
Fixes #1763 CSqlDataProvider order by bug
Merge pull request #1970 from szako/1763-CSqlDataProvider-order-by-bug

Fixes #1763 CSqlDataProvider order by bug