Backslash after alias causes 'Invalid path alias' exception in `\yii\BaseYii::getAlias`

Added support for arbitrary operators to Query::filterWhere, added support for arbitrary operators to Sphinx extension

- Removed `FileLoader` and used `\Twig_Loader_Filesystem` instead.
- Added support of Yii's aliases.
- Added `set()` that allows setting object properties.

Updated guide

fixes #4482

not sure about L421

INSERT queries didn't work with first letter capitalized in table name.

double word "from"