Length check.

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

Tiny Change - Typo

Second Example should start with ProgressBar::begin not ProgressBar::widget

use alias format for table names

Refactored ActiveRecord::find() so that find(null) will also return an ActiveRecord instance instead of ActiveQuery.

Fixed phpdoc, removed unit tests for Formatter asRelativeTime that were relative to current time since it was impossible to specify correct expected values

Fixes #2911: Removed `tbl_` default for table prefix

Refactor errorhandler

* master:
  Fixes #2912: Relative view files will be looked for under the directory containing the view currently being rendered
  app end improvement.
  improvement of Application::end() handling.
  typo fix.
  Fixes #2910: Added `Application::end()`

Conflicts:
	framework/base/Application.php

fixes #1946