Product filtering for Shop-Script

- Have added new functionality, for setting "Improve filtration" on frontend for plugin, rebuild functionality in new way for 8 and 9 version of Webasyst have used only own base classes for each version
- New functionality start working only from version ShopScript 9.3.0
- Big thanks Voaacho for finded mistake
- Has improved plugin

- Has rebuilt code in the best format
- Has changed select queries addJoin for more correct sql format for Stocks and Lists
- Thanks Dmitry for founded mistake

- Fix syntax error in select option 'By counts' by 'total sales', in this case plugin worked incorrect
- Fix js select for inside select, in some cases after second time category popup was opened, js functionality worked incorrect

- Add functionality for stocks, filtering products for each stock if count of products exist and more than zero

- Have added new type of filtration by Stocks
- In filtration type search by string have added new search types by short description and url
- In filtration type by date has added ability add last date without previous, also added clean button for previous date
- Has rebuilt filtration types by Types, Lists, Badges, Managers, all of this formats could use multi chose
- In filtration type by Badges has added ability filtering by your badge
- Has rebuilt code in the best format

New experimental functionality, that improve category filter in frontend after using plugin product filtering, this option for the correct working filters block in frontend category as for 'static' and 'dynamic' types of category, all filters apply for correct sorting products in category, more information in plugin documentations

Created plugin "Product filtering"

First version released.