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
doc fix [skip ci]
Fixes #2303: support setting basePath and baseUrl as aliases during runtime.
Fixes #735: Added back `ActiveField::hiddenInput()`
message fix. [skip ci]
Fixes #2571: Fixed the bug that batchInsert will fail for SQLite if the values contain null or boolean false;
Fixes #2683: Fixed the bug that batchInsert will fail for MySQL if the values contain boolean false.
Fixed test break.
test break fix.
Fixes #2729: Added `FilterValidator::skipOnArray` so that filters like `trim` will not fail for array inputs