sub menus didn't get checked for being active.

Based off the method in ```Menu.php``` I've updated ```Nav``` so it will check if sub menus are active or not.
Improved check for active child items

Updated to avoid full tree traversal.
Also noticed ```activateItems``` didn't do anything so that's been fixed.
Update CHANGELOG.md
Added asElapsedTime function
Typo in asElapsedTime description
Call Yii::t everytime instead of passing a template variable
Typo
asElapsedTime can now take DateInterval as parameter
asElapsedTime style improvements
asElapsedTime can now take a DateInterval string as a parameter
Added support for inverted intervals (future time) and unit tests
Removed debug code, changed doc
Modified example in DataReader usage comment to reference a DB Command function which accepts a SQL string argument.
PSR-2 compliance
Fixes #2775: Added `yii\base\Application::bootstrap` to support running bootstrap classes when starting an application
Mistake in error message

{max} was used instead of {min} in the error message for the min validator...
Merge pull request #2783 from docsolver/patch-2

Mistake in error message
updated composer documentation
Merge commit '1ccad3d97db122b71b84f222807e547b86687a12' into feature/composer-docs
Merge pull request #2784 from schmunk42/feature/composer-docs

updated composer docs