Fixes #3399: Added support for MS SQL Server older than 2012
Fixes #3241
Fixes #3744: `yii\db\Connection` now skips `bindValues` if there are no parameters to bind
Finished validation guide [skip ci]
typo fix [skip ci]
Fix #3749: Ensure clickable links for Bootstrap Dropdown

The registerPlugin is not required.
Fix #3749: Ensure clickable links for Bootstrap Dropdown
Merge pull request #3750 from kartik-v/patch-6

Fix #3749: Ensure clickable links for Bootstrap Dropdown
Fix PostgreSQL enumValues

$column->enumValues is set to array[0 =>''] even if $info['enum_values'] is null.
Gii generates always dropDownList in forms.
Revert "Fixes #3744: `yii\db\Connection` now skips `bindValues` if there are no parameters to bind"

This reverts commit ea10ba4938f44e30c5d3754c43f8a312a91daabc.
basic application template tests adjusted
Fixes #3752: `QueryBuilder::batchInsert()` does not typecast input values
application advanced template tests fixed
fixtures folders added
basic application template fixtures added
README info update
tabs to spaces unacceptable fix
refactored logger to support array values out of the box.

fixes #3245, #3244
fixed reset password token test
fixes display of array log messages in debug toolbar

fixes #3244