For Opencart v3.0.0.0+

This is simple modification which will add much needed ability to
run install.sql install.php files when installing extra extensions on your
shop.

This functionality was in the previous versions of Opencart (up to 2.3),
but it's missing in the new version (3+) for now.

Some extensions need this functionality for adding extra tables in the database
or initializing some data, but you should use it only when installing a trusted
extension (used in your shop before or extension with positive feedback and
supportive developer).

I would suggest the following steps:

1. install the "Extension Installer Extender"
2. install the Trusted extension which you need
3. uninstall the "Extension Installer Extender"

this way you are protected from malicious extensions, but please be careful.

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Take a look on my other extensions