New truncate and truncateWords methods

New truncate and truncateWords methods, https://github.com/yiisoft/yii2/issues/2941
Update BaseStringHelper.php

Length check.
Update CHANGELOG.md
Update BaseStringHelper.php

Updated to use mb_* functions
Test case for new truncate methods.

Test case for new truncate methods.
Add wait() to login test with wrong credentials to fix WebDriver test
removed redundant whitespace
Update logging.md

Currently `Yii::$app->log` is not the `yii\log\Logger`, but the `yii\log\Dispatcher`. Logger is transient component used indirectly and separately by the dispatcher and helper methods for logging.
Merge pull request #2980 from lubosdz/master

removed redundant whitespace, related to issue #2978
Add SyslogTarget
Clarify new usage of yii\web\View::render()

One paragraph description and one code snippet to clarify usage of yii\web\View::render() in a view context, as using echo is a significant change from partial view usage in Yii 1.1.
Merge pull request #3001 from hiltonjanfield/patch-1

Clarify new usage of yii\web\View::render()
doc fix [skip ci]
Very slight edits
Fix "Web"

Because we’re using capital “Web” not “web” (my previous mistake).
Pretty minor edits
More minor edits
Very trivial edits

Still feels like an incomplete, possibly unnecessary, fragment
First round of edits

Note: should confirm that my additions of “inclusive” is correct.
Refactored AR find